Volume 38, Issue 2019

In this paper, a blast furnace gas flow distribution model with variable furnace structure was founded based on CFD (computational fluid dynamics) theory, and the gas velocity distribution near the surface of the copper staves in different areas of the BF is calculated under different conditions of variational structure parameters like Bosh angle, shaft angle, and the newly proposed “equivalent Bosh angle.” Based on the calculation, the influence rule of the BF structure on the service life of copper stave and the corresponding operation measures were obtained. The result shows that the increase of the Bosh angle and the decrease of the shaft angle will incur increasing of the gas flow velocity near the surface of the copper staves, which is harmful to the cooling stave life; the variation of the equivalent Bosh angle has a most significant influence on the cooling stave life, and the increase of the equivalent Bosh angle will cause a sharp increase of the gas flow velocity, which will damage the copper staves seriously; adopting long tuyeres and minishing the equivalent Bosh angle will reduce the washing action of the gas flow and ensure the stability of slag hanging to achieve a long service life of copper staves.

The present research was aimed at determining the effects of the oxide layers on hydrogen absorption, microstructure and mechanical properties of the Zircaloy-2 and Zr 702 alloys. The oxidation was made at 350 °C, 700 °C and 900 °C for 10 to 30 min in laboratory air, followed by hydrogen cathodic charging for 72 h and annealing at 400 °C for 4 h. The slow strain rate tests were carried out on oxidized, charged and annealed specimens. The oxidation resulted in thick and cracked, more for Zr 702 alloy, layer. After oxidation at 350 °C, the appearance of hydrides in Zircaloy-2 and absence of hydrides in Zr 702 alloy were observed. After oxidation at high temperatures no current flow was noticed at applied voltage up to 5 V, and no hydrogen or hydrogen cracks. The observed effects were attributed to the phase structure of investigated alloys at low hydrogen content.

Laser hardfacing were produced using a high power Disk laser of 4 kW maximum power as a heat source to melt and bond the Colmonoy-5 powder on to AISI 316 LN stainless steel substrate. Significant difference in melting points between the austenitic stainless steel (ASS) substrate and Ni-based Colmonoy alloy results in substantial dilution of the hardfaced deposit from the substrate. In this present study, the effect of travel speed (TS) on microstructure, microhardness and wear characteristics laser hardfaced deposits were investigated. The phase constitution, microstructure and hardness of laser hardfaced deposits were examined by optical microscope, scanning electron microscope, energy dispersion spectroscopy, x-ray diffraction and Vickers hardness tester. The TS was varied between 300 and 500 mm/min. The other parameters such as, laser power, powder feed rate, and defocusing distance were kept constant. From this investigation, it is found that the deposit hardness increased from 750 HV to 800 HV with decreasing in TS. The TS increases, bead height decreased and dilution and depth of penetration increased. Due to higher TS the faster cooling rate takes place, it causes the cracking and porosity. Microhardness and wear resistance are slightly improved in the TS of 400 mm/min. The microstructures of deposit layer are composed of Ni-rich carbide, boride and silicide, this are the responsible for higher hardness and better wear resistance.

The influences of coal rank, particle size, temperature and gasifier atmosphere on the gas generation of lump coals used in COREX gasifier were investigated. The results showed that an increase in gasifier temperature and a decrease in particle size hardly affected the final mass loss of lump coals but strongly enhanced the gas generation rate. When the temperature was greater than 1000 °C, a decrease in coal rank increased the gas yield but had little effect on the gas generation rate. Moreover, the promotion ability of the atmosphere for the gas generation rate of lump coal from low to high was as follows: N 2 , CO 2 , CO and H 2 . Considering energy conservation, to improve the gas generation rate of the gasifier, the coal rank and particle size should be decreased first, and afterwards, an increase in reduction potential of the atmosphere in gasifier is also encouraged.

The actual combustion rate of pulverized coal in the blast furnace tuyere is hard to be measured. In this research, the combustion rate of pulverized coal injected into oxygen blast furnace was obtained by a new equipment. This equipment can simulate the actual blast furnace well, and the relationship between pulverized coal injection (PCI) ratio and A O/C was established by mathematical deduction. The experimental results show that the best combustibility of the four pulverized coals is C, and when the coal injection ratio is 350 kg/tHM, the combustion rate can be reached 79%, while the combustion rate of B in the same case is only 45.6%. With the increase of A O/C , the relative amount of oxygen to coal increases, the combustion conditions become better, and combustion rate of the pulverized coal increases. In addition, under the condition of high temperature and rapid combustion, with the increase of coal’s volatile, the combustion rate increases and the corresponding PCI ratio is also increased. By using the new equipment, the unburned coal under the oxygen blast furnace conditions can be collected for further study.

To effectively increase the dephosphorization efficiency of hot metals or the previous stage in the converter steelmaking process, phosphate capacities (CPO43−){\rm{(}}{{\rm{C}}_{{\rm{PO}}_4^{3 - }}}) of CaO–FeO–SiO 2 –Al 2 O 3 /Na 2 O/TiO 2 slags at 1300–1400°C were examined by laboratory experiments using equilibrating slag and pure solid iron foil. The data suggested that (CPO43−){\rm{(}}{{\rm{C}}_{{\rm{PO}}_4^{3 - }}}) increases with decreasing temperature and increasing slag basicity. Compared to basicity, temperature considerably affected the phosphate capacities and tended to be the most important factor. The phosphate capacities of slag considerably decreased at a high temperature of 1400°C even under high binary basicity as well as high contents of Na 2 O and FeO. Moreover, with the increase in the content of FeO and Al 2 O 3 in the slag, (CPO43−){\rm{(}}{{\rm{C}}_{{\rm{PO}}_4^{3 - }}}) decreased. A low content of Na 2 O led to the increase in the phosphate capacities of slag, particularly at low temperatures of 1300–1350°C. The content of TiO 2 in the slag considerably exhibited a weaker effect on (CPO43−){\rm{(}}{{\rm{C}}_{{\rm{PO}}_4^{3 - }}}). Furthermore, by regression analysis, (CPO43−){\rm{(}}{{\rm{C}}_{{\rm{PO}}_4^{3 - }}}) was expressed as a function of the temperature and slag compositions as follows: logCPO43−=0.041(%CaO)−0.086log(%FeO)−0.024(%SiO2)−0.02(%Al2O3)+0.067(%Na2O)+0.039(%TiO2)+56767/T−14.58,(R=0.978)\eqalign{&{{\rm{log}}{{\rm{C}}_{{\rm PO}_4^{3 - }} = 0.041( \% {\rm CaO}) - 0.086{\rm log}({\rm{ \% }}{\rm FeO})} - 0.024( \% {\rm Si{O_2}})} \cr &{{ - 0.02({\rm{ \% }}{\rm A{l_2}{O_3})}} { + 0.067( \% {\rm N{a_2}O)} + 0.039( \% {\rm Ti{O_2})}}} \cr &+ 56767/{\rm T} - 14.58, ({\rm R} = 0.978)}}

WC flexible cloth was fabricated by rolling WC powder that was pre-mixed with a nano-scale binder. BNi-2 braze alloy was used to braze the WC flexible cloth to a workpiece surface in a vacuum to form a compact composite coating. The composite coatings with different percentages of WC (wt.%, 30 %, 50 % and 80 %) have been successfully brazed onto Q345 steel substrate. Microscopic morphology and interfacial structure were characterized in terms of porosity, segregation and the distribution of WC particles. The bonding strength between the coating and the substrate was evaluated by shear test. The results showed that the segregation of WC particles appeared in all three coatings. With the increase of WC content in the coating, the segregation phenomenon was gradually reduced, and the WC particles were more closed. Furthermore, the thickness of the coating and matrix reaction layer was narrower, and more holes were found in the coating. Fracture of the 30 % and 50 % WC coatings was mainly plastic fracture, and the fracture of the 80 % WC coating was mainly brittle fracture accompanied by local plastic fracture. The maximum bonding strength of the coating to the substrate was determined to be 302 MPa.

Refill friction stir spot welding (RFSSW) was used to join 6061-T6 and 7075-T6 aluminum alloys in this work. Different sheet configurations and welding parameters were used to optimize joint strength. The effect of sleeve plunge depth on the microstructure and mechanical properties of the joints were investigated. The results showed that no defects were obtained when 6061-T6 aluminum alloy was placed as the upper sheet. The lap shear failure load of the joint using 6061-T6 aluminum alloy as the upper sheet was higher than that using 7075-T6 as the upper sheet. The maximum failure load of 12,892 N was attained when using the sleeve plunge depth of 3.6 mm. The joint failed at the upward flowing 7075 near the hook.

The monodisperse Ni 0.5 Zn 0.5 Fe 2 O 4 nanospheres have been synthesized via a simple solvothermal method. The effects of reactant concentration on structural and magnetic properties have been studied. X-ray diffraction analysis results indicate that the lattice constant and crystallite size can be tuned by controlling reactant concentration. The nanosphere size monotonically decreases from 238 to 35 nm with increasing reactant concentration. The magnetic studies show that blocking temperature is enhanced, and these single-domain particles are superparamagnetism at room temperature. The hollow nanospheres exhibit a high saturation magnetization value of 52.6 emu/g. The nanospheres with various diameters exhibit different magnetic saturation values which may be caused by the domain structure, surface effects and the distribution of metal ions on A and B sites. These superparamagnetic Ni 0.5 Zn 0.5 Fe 2 O 4 nanospheres are expected to have potential application in biomedicine and magnetic fluid technology.

In this study, the logarithmic-power model has been used to predict hot deformation behavior of alloy 800H at high temperatures. This is for the first time that the logarithmic-power model is examined to model the flow stress curves with negligible flow softening at high strain rates. To this end, flow stress curves of alloy 800H obtained at deformation temperatures from 850°C to 1050°C and at strain rates of 5 and 10 S −1 were employed. The Johnson–Cook model and Shafiei constitutive equation were also used to prove the accuracy of the logarithmic-power model in prediction of flow stress curves of alloy 800H. Evaluation of mean error of flow stress at different deformation conditions showed that the logarithmic-power model can give a more precise estimation of flow stress curves than Johnson–Cook model. Furthermore, it was found out that the accuracy of the Logarithmic-power model and Shafiei constitutive equation was roughly the same in terms of maximum errors obtained in prediction of flow stress curves. Accordingly, it can be concluded that the logarithmic-power model can be employed as a comprehensive model for a wide range of deformation conditions.

A novel 3D conductive heat transfer model was developed based on node temperature inheritance. Heat transfer of the mold and billet could be analyzed synchronously. In the model, heat transfer in the copper wall was in a steady state, whereas heat transfer in the billet was in a transient state. The temperature distribution indicated that the maximum temperature on the copper wall reached approximately 30 mm below the meniscus. The results were in better agreement with industrially measured data than those of traditional 2D heat transfer models. The model was applied to study the effect of water scale on heat transfer of a billet mold. When the scale thickness increased from 0 to 0.5 mm, the maximum temperature on the copper wall increased from 174 °C to 364 °C, which will lead to mold deformation and peeling of the coating. In addition, the shell thickness slightly decreased with increasing scale thickness.

To investigate the structural characteristics and mechanical properties of minerals in vanadium-titanium sinter, the 3D microstructures of the sinter were reconstructed by serial sectioning in conjunction with computer-aided 3D reconstruction techniques The results show that hematite and magnetite in vanadium-titanium sinter will grow along the longitudinal axis direction and act as a scaffold. The size of magnetite crystals in vanadium-titanium sinter is much smaller than that in traditional sinter. The calcium ferrite in vanadium-titanium sinter is columnar-like, while that in traditional sinter is needle-like. The decreasing order of the microhardness value of minerals in the two sinters is hematite, calcium ferrite, magnetite and silicate, while the fracture toughness value from highest to lowest is calcium ferrite, hematite, magnetite and silicate. The comprehensive hardness value and comprehensive fracture toughness value of vanadium-titanium sinter are both less than these of traditional sinter.

The effect of cooling rate on martensitic structure and carbides precipitation behavior was investigated based on Cr-Mo alloy steel with different quenching media of oil, water and 10% NaCl-water, respectively. The influence mechanism of martensite structure and carbide precipitates on mechanical properties was also studied. The results showed that martensite packets and blocks were refined with water quenching, however, they were coarse with oil or 10% NaCl-water quenching. Martensite laths were refined and dislocation density increased with increasing cooling rate. The carbides in tempered steel were coarse obviously with 10% NaCl-water quenching. The impact toughness deteriorated significantly with 10% NaCl-water quenching due to coarsening of martensite structure and carbides.

Thermal barrier coatings (TBCs) as a kind of temperature-resistance materials have been widely applied in super high temperature components in aircraft engines. However, TBCs are subjected to harsh service environment such as high temperature oxidation and erosion, which lead to the coating failure. It is important to investigate the effect of fire temperature, angle and velocity of particle on erosion to understand the failure mechanism. In this paper, the temperature and velocity distributions of erosion particles in high temperature gas burner rig are investigated by using the fluid–solid coupling method with the discrete random walk model . The results show that a non-uniform distribution of temperature appears in different positions of the central axis, and the temperature of particle is affected obviously by the gas stream and particle size. The trajectory of particles and velocity diagrams under different particle size are determined by coupling the continuous phase with the erosion particles.

Permittivity is a vitally important parameter for describing the absorbing and heating characteristics of a material under microwave irradiation, and it is also strongly dependent on temperature. However, the literature contains little information on this topic and even less particular permittivity data at elevated temperatures. In this paper, the permittivity of a CuCl residue at temperatures from 13 to 450 °C at 2.45 GHz was measured using the cavity perturbation method. The relationship of its real part ( ε′ ) and imaginary part ( ε″ ) with temperature ( T ) was deduced. In addition, the temperature-dependent tangent (tan δ ) and the penetration depth ( d ) of microwaves into the material were calculated. The results of the permittivity study show that the dielectric constant ( ε′ ) of the CuCl residue increased linearly with increasing temperature. In contrast, the dielectric loss factor ( ε″ ) and loss tangent first maintained on a steady value between 13 and 300 °C and then substantially increased from 300 to 450 °C. The positive interaction of the dielectric property and temperature showed the reasonableness of our earlier metallurgy process, where the CuCl residue for dechlorination was roasted at 350–450 °C under microwave irradiation.

In order to improve the reduction rate of titania in molten iron, various iron powders containing C, Si, Mn and S were melted. The experiments were carried out on the reduction of titania through a high-temperature tube furnace at 1,723–1,823 K. The quantitative effects of C, Si, Mn, S and temperature on the reduction of titania were investigated in the current study. The results demonstrated that when the carbon content, the manganese content and the temperature increased by 1 %, 0.1 % and 100 K, the reduction rate increased by 0.008 %/h, 0.001125 %/h and 0.0235 %/h, respectively; when the sulfur content increased by 0.01 %, the reduction rate decreased by 0.004875 %/h; the reduction rate was irregular with the change of silicon content in molten iron. The phase at the reaction interface after the experiment was confirmed to be the Fe 2 Ti 3 O 9 which was considered to be the combination product between iron oxide and titania; the lower titanium oxides were unstable and hard to be observed. The reduction was affected by the concentration of various elements in molten iron and the activity interaction coefficients between various elements. The rate constants for reduction were calculated at 1,723 K, 1,773 K and 1,823 K; the apparent activation energy was calculated as 209 kJ/mol through the rate constants and temperatures according to the Arrhenius equation.

The interdiffusion in Ti-based alloys was studied. It was shown that during diffusion at 1,123 K formation of four intermetallic phases occurs. The diffusion paths for six different diffusion couples were determined. Moreover, the entropy production was calculated – the approximation used for determination of the sequence of intermetallic phase formation. In theoretical analysis, the intrinsic diffusion coefficients were determined from the modified Wagner method.

New results about the growth kinetics of CoB–Co 2 B layers developed at the surface of CoCrMo alloy using the powder-pack boriding process assisted by a direct current field (PBDCF) were estimated in this work. The PBDCF was conducted at temperatures of 1048 – 1148 K with different exposure times for each temperature, whereas the growth kinetics of the cobalt boride layers was modelled using a system of two differential equations. In addition, indentation properties such as hardness, Young’s modulus and residual stresses were estimated along the depth of the borided CoCrMo surface. The growth kinetics of the cobalt boride layers developed by PBDCF indicated that thicker boride layers were formed on the material’s surface which was in contact to the current field at the anode, in contrast to the surface exposed at the cathode. The kinetics of cobalt boride layers were compared with those obtained by conventional powder-pack boriding process.

In this study, the high-temperature deformation behaviour of a TC17 titanium alloy was investigated by isothermal hot compression tests in a wide range of temperatures (973–1223 K) and strain rates (0.001–10 s −1 ). Then, the constitutive equations of different phase regimes (α + β and single β phases) were developed on the basis of experimental stress-strain data. The influence of the strain has been incorporated in the constitutive equation by considering its effect on different material constants for the TC17 titanium alloy. Furthermore, the predictability of the developed constitutive equation was verified by the correlation coefficient and average absolute relative error. The results indicated that the obtained constitutive equations could predict the high-temperature flow stress of a TC17 titanium alloy with good correlation and generalization.

The effects of both the microstructure and the original grain size on three-roll screw rolling process of Ti6Al4V titanium alloy bar were studied in the present work. The microstructure of Ti6Al4V titanium bar had a great influence on the mechanical properties of the rolling bar. When the original size was large, the grains were apparently refined but the microstructure was uneven. But for semi-finished titanium bar composed of fine equiaxed grains, the grains after rolling were fine and uniform. During the rolling process, the Ti6Al4V titanium alloy microstructure changed from equiaxed structure to the basket-weave one. After annealing at 800℃ for 1.5 hours and then cooling in air, the average tensile strength decreased from 984 MPa to 964 MPa; while after annealing at 950℃ for 1.5 hours and then cooling by water, and aging at 540℃ for 6 hours then cooling by air, the average tensile strength increased from 979 MPa to 1107 MPa.

The phase transformation behavior of crack-arrest steel during continuous cooling either with or without deformation at high temperatures was investigated. By carefully examining the microstructures of continuous cooled samples, we found that pearlite, quasi-polygonal ferrite (QPF), acicular ferrite (AF), granular bainite (GB), upper bainite, lath-like bainite and martensite/austenite will exist depending on cooling rates and transformation temperatures in both conditions of deformation and without deformation after austenization. The transformation curves of AF and GB moved toward the left in deformation condition in comparison with that of without deformation condition, which indicated that deformation promoted the formation of QPF and AF; meanwhile, deformation inhibited the formation of bainite. Finer bainite and the accompanying M/A could be obtained by reducing the bainite nucleation activation energy as follows: (i) increasing the undercooling by increasing the cooling rate; (ii) increasing the stored energy by deformation of the austenite.

Based on the stress characteristics of primary solidified shell in the mold, formation model of the shell’s sticker is established according to the theory of mechanical strength, and the mechanism and internal factors of the shell tearing are analyzed by the model. Furthermore, based on the measured data of many stickers in a slab-continuous caster, the influence of casting process factors on the sticker is analyzed statistically. The possible causes for the stickers in the studied caster are discussed. The results provide a reference for optimizing the continuous casting production process and effectively preventing the occurrence of the sticker from the source.

In this study, Cu/Al composite castings were prepared using the pouring aluminum method, and the casting defects in the transition layer and their formation mechanism were investigated. Shrinkage cavities, shrinkage porosities, and cracks were easily formed in the transition layer, and the thickness of the transition layer was uneven after recombination of the solid Cu and liquid Al. Shrinkage cavities easily formed within the α + eutectic (α + CuAl 2 ) phase, and cracks mainly appeared within the Cu 9 Al 4 and CuAl 2 phases. The transition layer with uneven thickness and irregular shape readily formed where the metals solidified last during the solidification; the difference in density between solid Cu and liquid Al, as well as the natural convection in the melt, were responsible for these irregular shapes. As the metals shrunk, shrinkage cavities and porosities formed without external melt feeding. Cracks formed in the Cu 9 Al 4 and CuAl 2 phases and at the Cu 9 Al 4 /CuAl 2 and CuAl 2 /eutectic (α(Al + CuAl 2 ) interfaces during the solid shrinkage process after the solidification was complete.

Three dual alloy ingots were processed by electroslag remelting with 1500 A, 1800 A and 2100 A. The compositions and inclusions of ingots were analyzed by means of various analytical techniques. The results show that the segregation becomes severer with the increase of current. With the current increasing, the proportion of inclusions with large size, the T.[O] and sulfur content in the ingot increase, showing a worse cleanliness due to the severer electrode surface oxidation and shorter interaction time between slag pool and film of molten steel at the electrode tip. The single (Mn,Cr)S inclusion can precipitate in transition zone of each ingot and NiCrMoV zone of ingot with 1800 A and 2100 A due to higher sulfur content and the solute segregation during solidification. The ingot processed by ESR with 1500 A performed a balanced quality.

The AISI 1518 steel was pack-borided in the temperature range 1123–1273 K for a treatment ranging from 2 to 8 h. A compact single boride layer (Fe 2 B) was formed at the surface of the AISI 1518 steel using the mixture of powders composed of 20 % B 4 C, 10 % KBF 4 and 70 % SiC. The following experimental techniques such as scanning electron microscopy coupled with EDS analysis and X-ray diffraction analysis were employed to characterize the pack-borided AISI 1518 steel. An alternative model, based on the integral mass balance equation, was used to estimate the boron diffusion coefficients in the Fe 2 B layers in the temperature range 1123–1273 K. Finally, the value of activation energy for boron diffusion in the AISI 1518 steel was estimated and compared with the literature data. Furthermore, the present model was validated by comparing the experimental value of Fe 2 B layer thickness, obtained at 1253 K for 2 h of treatment, with the predicted value.

Microstructure, hardness, precipitates and phase transformation on the X-Y surface of Inconel 718 Ni-based alloys fabricated by selective laser melting (SLM) were studied before and after a suitable heat treatment. The test results show that the obvious weld beads structure was observed on the surface of the as-built alloys, and the microstructure shows seriously inhomogeneous with distributing columnar crystals and fine dendrites. When the 720°C, 3 h/furnace cooling+620°C and 3 h/air cooling was used, the columnar and small dendritic crystals begun to transform into bulk crystals, and the weld beads structure disappeared instantly. The X-Y surface hardness of alloys is about HV490-540, which is higher than the one of other heat treatment processes. With the increase of solid solution temperature, the microstructure on the surface of alloys shows an obvious refining characterization. The hardness value on the surface was also reduced gradually. The typical columnar crystals, dendrites, intermetallic compounds and precipitated hardening phase (Cr-Fe-Mo-Ni, FeNi and Ni 8 Nb) were also reduced or could not be found. Under the solid solution process of 950°C, the fine homogeneous δ phase and γ′ phase in the grain or near the grain boundary had an important effect on the suitable surface hardness value (HV476-500) of alloys.

In this article, manganese-doped cobalt oxide (Mn-doped Co 3 O 4 ) thin films have been prepared on glass substrates using sol gel-based dip-coating technique in order to investigate their optical, structural and electrical properties. The Mn concentration was changed from 0 % to 9 %. The synthesized samples were characterized by ultraviolet-visible spectroscopy (UV-visible), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and complex impedance spectroscopy to elucidate the optical, structural, vibrational and electrical properties. Our optical results show that the transmittance of Mn-doped Co 3 O 4 films decreases with increasing doping levels. The optical band gaps were found to be (Eg1=1.51 eV,Eg2=2.12eV)({E_{g1}} = 1.51{\ }eV, {E_{g2}} = 2.12{\rm{ eV}}) and (Eg1=1.23 eV,Eg2=1.72eV) ({E_{g1}} = 1.23{\ }eV, {E_{g2}} = 1.72{\rm{ eV}}){\ }for the case of undoped Co 3 O 4 and 9 % Mn-doped Co 3 O 4 , respectively. This shift means that the impurities would create energy levels. The structural analysis provides evidence that obtained powders were crystallized in cubic spinel structure. The complementary phase information is provided by FTIR spectroscopy. The FTIR study depicted the presence of four distinct bands characterizing Mn-doped Co 3 O 4 cubic spinel-type structure. The Nyquist plots suggest that the equivalent circuit of Mn-doped Co 3 O 4 films is an RpCp parallel circuit. It was found that the effective resistance Rp decreases, whereas the effective capacitance Cp increases with doping.

Plasma transferred arc welding (PTAW) is one of the outstanding overlay coating technique used in numerous industries including pressure vessel, automotive, chemical, nuclear, etc. owing to its superior characteristics, low dilution and high efficiency in the coating. In the present investigations, an effort is made to investigate the multitrack overlay deposition by PTAW on 16 mm thick 316 L plate by CO-Cr alloy. Samples are produced under different processing conditions, as per full factorial central composite design of experiment with preheating of 200°C by maintaining the interpass temperature 250 °C. Effects of transferred arc current, welding travel speed, powder feed rate, welding oscillation speed and stand-off distance on weld bead shape parameters comprising of width of deposition and reinforcement are presented and discussed based on experimental observations and fitted model. Relationship between the input process parameters with deposition characteristics is also presented in the form of regression equation. Lower current (100–120 A), intermediate travel speed (120–140 mm/min), intermediate powder feed rate (12–14 gms/min), lower oscillating speed (450–550 mm/min) and lower stand-off distance (6–8 mm) would give better deposition characteristics with minimum distortion, less residual stresses, no surface defects with strong metallurgical bond.

This paper studies on the dependence of the mean nearest neighbor distance, the Young modulus E , the bulk modulus K , the rigidity modulus G and the elastic constants C 11 , C 12 , C 44 on temperature, pressure, the concentration of substitution atoms and the concentration of interstitial atoms for alloy AuCuSi (substitution alloy AuCu with interstitial atom Si) with FCC structure by the way of the statistical moment method (SMM). The numerical results for alloy AuCuSi are compared with the numerical results for main metal Au, substitution alloy AuCu, interstitial alloy AuSi, other calculated results and experiments.

The high-temperature simulation tests of softening and melting zone under different w (Cl - ) were carried out, and based on the density functional theory, the influence mechanisms of chlorine on softening and melting behaviors of BF burden were analyzed. The results show that with the increase of w (Cl - ) which bring in by sinter, the softening start temperature and softening end temperature of BF increase, and the softening temperature range becomes small, the melting start temperature increases, the dropping temperature decreases, the melting temperature range becomes small too. The softening and melting zone of BF narrows. With the increase of w (Cl - ), the maximum pressure difference and the comprehensive permeability index both decrease, the permeability of the softening and melting zone enhances. The main reason for the increase of permeability is that the chlorine atom makes the Fe-O bond length increase, the stability of the structure is destroyed, the adsorption capacity of CO molecule on FeO surface is promoted, the reducing speed of FeO increases. Although chlorine can effectively reduce the reduction degradation of sinter in the BF and improve the permeability of the softening and melting zone, the metallurgical enterprises should still eliminate or reduce the chlorine element into the BF.

The effects of the simultaneous injection of MgO and magnesite powder on the combustion of coals, properties of the primary slag, and softening-melting properties of the burden were investigated. There were four aspects to the results that we obtained. First, MgO showed catalytic activity for dehydrogenation and carboxyl group removal from coal; as a result, with increasing MgO, the combustion ratio and pyrolysis ratio of the coal investigated improved. Notably, when the content of MgO increased from 0% to 3.21%, the combustion ratio increased from 67.75% to 75.73%. Secondly, the MgO distribution in the slag sample was close to that in the standard slag after melting for 10 min. After 50 min, the difference in MgO content between the slag and standard slag samples was less than 1%. Thirdly, with an increase in the content of MgO, the short-slag feature of the slag was obvious, the viscosity fluctuated wildly, and the melting temperature increased significantly. It is proposed that the properties of the primary slag could be improved by decreasing the MgO content. Finally, with the increase in the MgO added to the burden, the softening-melting properties of the burden degraded. When the MgO content was 0.86%, Δ P max was only 2.04 kpa, and S 59 kPa·°C. However, when the MgO content was 2.61%, Δ P max was 20.00 kPa, and S 1349 kPa·°C. Therefore, the technology of MgO injection into tuyeres with pulverized coal was beneficial for blast furnace operation.

Although steel slag exhibits cementitious properties, the addition of steel slag in cement is still limited due to both the presence of excess iron oxides and instability of free lime and periclase. This paper proposes a method for oxidizing molten slag in air, aiming at extraction of superfluous wustite and stabilization of free lime and periclase. Mineralogical characteristics of raw slag and modified products were examined using X-ray diffraction (XRD), scanning electron microscopy equipped with backscattered electron imaging (SEM-BEI), energy dispersive spectrometry (EDS) and thermogravimetric analysis (TGA) with differential scanning calorimetry (DSC). Thermodynamic calculations were performed to aid to discuss the experimental results. The results indicate that non-magnetic wustite and periclase are transformed into magnetic spinel (magnetite/magnesioferrite) after oxidation. Temperature has a significant effect on the formation of spinel. The mass fraction of free lime decreases from 3.54 wt.% to 0.96 wt.% as a result of the conversion from free lime to calcium ferrite.

The present study deals with a microwave-assisted oxidation roasting oxide–sulphide zinc ore technology of with addition of manganese dioxide. Effects of roasting parameters such as MnO 2 addition level, roasting temperature, and holding time are studied by using the Central Composite Design (CCD). Meanwhile, zinc calcines are characterized by phase compositions analyses(XRD), structure characteristics of minerals (FT-IR), micro-area chemical analyses (SEM-EDAX) and elemental valence bonding analyses (XPS), which prove to be in accordance with the CCD results. The optimum roasting conditions are decided as MnO 2 addition level being 85.14 %, roasting temperature 680 °C, and holding time 41 mins, and oxidation degree of zinc can reach 88.22 %. Besides, when MnO 2 addition level reaches a certain value, zinc will aggregate in a form of ZnMn 2 O 4 , one battery material.

The bubble migration in liquid titanium melt during vertical centrifugal casting process has been investigated by hydraulic experiments. Results show that the gas bubble in the simple cavity ultimately migrates like a line parallel to the wall in the opposite direction to the rotational casting mould. The deviation distance of the bubble in the simple geometry cavity tends to increase with the increment of the mould rotational speed during the migration process. And the gas bubble is much easier to migrate like a line when its initial position is nearer to the casting mould wall which is opposite to the mould rotational direction. The migration trajectories of bubbles located at different position in the complex cavity are more complicated than that in the simple cavity. The casting mould in the complex cavity can hamper both the radial movement and the circular movement of the bubble. And gas bubbles will gather, re-nucleate and form new bigger bubbles beside the casting mould wall. The re-formed gas bubbles in the complex cavity become bigger than which escape from bubble generation chamber.

Four-millimeter thick A7N01-T4 aluminum alloy plates were welded by double wire metal inert gas welding (DWMW) in high welding speeds, ranging from 1100 to 1250 mm/min. The results show that a sound joint could be obtained at a high speed of 1200 mm/min using DWMW. The weld zone (WZ) in the joint showed a dendritic structure of equiaxed grains, and in the fusion zone (FZ), the microstructure existed as a fine equiaxed crystal structure about 100 µm in thickness. In the WZ adjacent to the FZ, elongated columnar crystal structure distributed along to the interface, and coarse microstructure in the heat affected zone (HAZ) were found, showing a typical rolling texture. The main precipitates in the WZ were assumed to be Fe-enriched phases, and Mg- and Zn-enriched phases. Tensile fracture generally occurred in the WZ adjacent to the FZ with a decrease in ductility, and it was consistent with the results of the microstructure analysis and hardness profile. The mean ultimate tensile strength and elongation of specimens were 302 MPa and 4.5 %, respectively.

ASTM-SA210-Grade A1 boiler tube steels were welded by shielded metal arc welding (SMAW) and tungsten inert gas processes. The oxidation behaviour of the welded steels was evaluated under cyclic conditions at 900°C. Visual observations and thermogravimetric data were measured at the end of each cycle. Finally, the scale was analysed using X-ray Diffraction, Scanning-Electron Microscopy/Energy-Dispersive X-Ray studies. A SEM Back scattered image analysis of the cross-section of the oxide scale thickness has been made to measure the oxide scales formed over the welded steels. SMAW welded steel showed the more oxidation rate (in terms of weight gain) as compared to TIG welded at the test temperature of 900°C and it was due to the formation of more cracks in oxide scale, and a thick oxide scale was found on HAZ and weld region.

It is a significant issue to deeply understand the nature relationships between damage degradation and deforming parameters, and then identify the changes of initial ductile fracture time with processing parameters and further adjusting the forming processes for obtaining the fracture-free components. For Ti-6Al-4V alloy, the strain-stress data in the temperature range of 1023–1323 K and strain rate range of 0.01–10 s −1 were obtained by compression tests. The finite element model with stress-strain data was constructed to simulate the ductile damage cumulating processes under different conditions and obtained the maximum damage values. Subsequently, the ductile fracture criterion (DFC) of Ti-6Al-4V alloy was established and the effects of temperature and strain rate on DFC were discussed. The results show that the variation range of DFC under different deformation conditions is 0.07–0.15. Subsequently, the deformation conditions with higher fracture risk were identified as 1200∼1275 K & 1∼10 s −1 and verified with the experiment observations.

Boriding of pure iron was investigated using the powder pack method with boriding powder mixtures containing different weight fractions of ZrB 2 (5 %, 10 %, 15 % and 20 %). The samples were borided in an electric resistance furnace for an exposure time of 4 h at 1,173 K temperature under atmospheric pressure. Borided samples were characterized by optical microscopy, X-ray diffraction analyses and microhardness tests. Results showed that the boride layers consisted mainly of FeB and Fe 2 B phases. No significant difference in boride layer thicknesses (average 140 μm) could be observed as a function of ZrB 2 content. The needle-like morphology of the boride layer became more prominent with increasing weight fraction of ZrB 2 in the boriding powders. The average microhardness of the boride layer decreased with increasing ZrB 2 content due to changes in the morphology of the boride layer.

To clarify the evolution of interfacial features between MnO-SiO 2 type inclusions and Si-Mn killed steel during isothermal heating at low temperatures, two diffusion couple samples were investigated under heat treatment at 1173 K and 1273 K, respectively. The experimental results show that the diffusion of oxygen from the oxide to the alloy is the restrictive link of the solid-state reaction between MnO-SiO 2 -FeO oxide and steel matrix at low heating temperatures. With increasing heating time or temperature, more FeO in the oxide decomposed, and the resulting oxygen diffused into the alloy and reacted with Mn and Si elements. The critical heating temperature at which the interfacial reaction can occur was determined to be 1173 K. And a dynamic model that predicts the change in the width of the particles precipitation zone at low temperatures was also established based on Wagner equation.

The effects of MgO, Al 2 O 3 , C/S (CaO/SiO 2 ) and FeO on the viscosity and the liquidus temperature ( T LQ ) of blast furnace (BF) primary slag were analyzed by using multiphase equilibrium. The results show that the T LQ of primary slag exhibits a minimum value at 12 wt% Al 2 O 3 and 14 wt% Al 2 O 3 when MgO contents are 8 wt% and 10 wt%, respectively. It can be suggested that the content of MgO in primary slag is prone to be retained at different value when Al 2 O 3 is different for smooth operation. The suitable value of MgO/Al 2 O 3 ratio increases with the increase of Al 2 O 3 content from 10 wt% to 18 wt% in the primary slag and the proper MgO/Al 2 O 3 ratio is 0.4–0.55. The T LQ of the slag increases with the increase of C/S when Al 2 O 3 content is lower than 14 wt%, while it decreases with the increase of the C/S when Al 2 O 3 is higher than 14 wt%. The slag viscosity decreases with the increase of FeO content. The isoviscosity curves become closer and closer when FeO is in a low level. In the condition of the high Al 2 O 3 content, improving the reduction degree of iron ore in the upper area of the BF can achieve a lower T LQ and have a smooth operation.

The microstructures and impact properties of the heat affected zone (HAZ) in steel treated by rare earth (RE) under different welding processes were discussed. The effect of Al on the impact properties of the HAZ in RE treated steel was analyzed. It finds that when the welding t 8/5 is smaller than 111 s, the main microstructure in steels is bainite/widmanstatten. The impact toughness of the HAZ is lower than that of the steel matrix. When t 8/5 is more than 250 s, the microstructure is mainly acicular ferrite (AF) in the steel treated by RE, and the impact toughness of HAZ is obviously improved. Even under the welding processing with t 8/5 about 600 s in RE treated steel can still obtain a lot of AF. While in the steel killed by Al and treated by RE, the main microstructure is parallel cluster of bainite/widmanstatten, and the impact toughness of HAZ is significantly lower than that of low-Al RE treated steel. Al can deteriorate the optimizing of RE treatment on HAZ.

Chromium carbide (Cr 3 C 2 ) coatings on the diamond were fabricated using the mixtures of molten salt of NaCl and BaCl 2 , powders of metallic chromium and diamond as raw materials in the temperature range of 750–900 °C by the microwave-assisted molten-salt synthesis. The morphology, microstructure and phase composition of the surface layer were characterized by Scanning Electron Microscopy, Energy-dispersive Spectrometry and X-ray diffraction. The results show that the surface of the diamond particles could be coated with Cr, forming a uniform and continuous Cr 3 C 2 -coated layer. The coatings thickness on the diamond can be controlled by adjusting the heating temperature and time. The coating thickness expanded from 0.73 to 2.30 µm when the temperature was increased from 750 °C to 900 °C, and increasing rapidly during the temperature range of 800  °C–850  °C, the coating thickness expanded from 1.30 to 2.80 µm when the holding time was increased from 0.5 h to 4 h. The results illustrate that the microwave-assisted molten salt synthesis plays a positive role in chromium coatings on the diamond, offering a potent method for the surface metallization of diamond.

This work conducted systematic studies on the effect of B on the hot ductility behavior of Fe-36Ni alloy over the temperature range of 900–1,200 °C by use of Gleeble-3500 thermal simulator, Thermo-Calc software, transmission electron microscopy and secondary ion mass spectroscopy. The influencing factors and mechanisms are also discussed in the present work. Results show that all the values of area reduction of the investigated alloy samples are below 60 % in the temperature range of 900–1,000 °C, indicating the poor hot ductility of the investigated alloys in this temperature range. When the grain boundary sliding occurs during the hot tensile processes, the fine secondary phase particles at grain boundaries prevent the occurrence of dynamic recrystallization and promote the nucleation and propagation of cracking simultaneously, resulting in the poor hot ductility of the investigated alloys in this temperature range. In the B bearing alloy, the segregation of B atoms around austenite grain boundaries promotes the solute dragging effects at grain boundaries and strongly inhibits the occurrence of dynamic recrystallization, which increases the brittle temperature to 1,000 °C. When the temperature exceeds 1,050 °C, the occurrence of dynamic recrystallization improves the hot ductility significantly. However, the coarsening of recrystallized grains and the formation of inter dendritic cracks decrease the hot ductility of the alloy gradually when the temperature increases from 1,100 °C to 1,200 °C.

Hypereutectic Al-Si melts and eutectic Al-Si melt were solidified to study boron and phosphorus distributions in primary silicon phase, eutectic silicon phase and eutectic aluminum phase during Al-Si solvent refining. The boron and phosphorus contents in the primary silicon phase and the eutectic silicon phase were determined by ICP-OES, and the boron and phosphorus contents in the eutectic aluminum phase were calculated by the principle of mass conservation. The primary silicon phase has lowest boron and phosphorus contents, while the eutectic aluminum phase has highest boron and phosphorus contents.

MgO–C refractory was polarized across the slag-refractory interface at a voltage of 8 V in a synthetic CaO–Al 2 O 3 –SiO 2 – (MgO) Slag at 1773 K. A deposition layer mainly composed of dicalciumsilicate (2CaO.SiO 2 ) or spinel (MgO.Al 2 O 3 ) with several hundred microns thick was achieved by cathodic polarization. However, the anodic decay was accelerated in comparison to the cathodic refractories and nonpolarized reference MgO–C refractories. The electrodeposition layer was mainly caused by the reduction of silicate anions, in which a shift of slag composition to the dicalciumsilicate (C 2 S) or spinel (MA) primary phase field was induced. Furthermore, the rapid migration of mobile Ca 2+ and Mg 2+ ions can also lead to the enrichment of CaO and MgO at the slag/refractory interface. The present voltage level (8 V) is acceptable for the economic considerations and the slag component also need a careful section for the corrosion protection of MgO–C refractories.

In this study, oxide dispersion strengthened (ODS) ferritic steels with nominal composition of Fe–14Cr–2W–0.35Y 2 O 3 (14Cr non Zr-ODS) and Fe–14Cr–2W–0.3Zr–0.35Y 2 O 3 (14Cr–Zr-ODS) were fabricated by mechanical alloying (MA) and hot isostatic pressing (HIP) technique to explore the impact of Zr addition on the microstructure and mechanical properties of 14Cr-ODS steels. Microstructure characterization revealed that Zr addition led to the formation of finer oxides, which was identified as Y 4 Zr 3 O 12 , with denser dispersion in the matrix. The ultimate tensile strength (UTS) of the non Zr-ODS steel is about 1201 MPa, but UTS of the Zr-ODS steel increases to1372 MPa, indicating the enhancement of mechanical properties by Zr addition.

In this study, the performance of a boron-rich Si-B system containing ~ 2–25 mol% Si is reviewed as a high-temperature thermoelectric material. In this review, both thermodynamic stability and transport properties are evaluated to understand the high-temperature thermoelectric performance of the Si-B system. The thermodynamic properties, such as Gibbs energy and activity coefficient, of the Si-B system were calculated and compared to the literature data. Thermoelectric properties such as Seebeck coefficient, electrical conductivity, and thermal conductivity were reviewed for the Si-B system. It is found that the composition and processing techniques are critical for obtaining higher thermoelectrical properties and thus also true for the figure of merit ZT. The entropy (degree of randomness) of a system has a remarkable effect on ZT. The highest ZT obtained for this system is approximately 0.2 at 90% B (SiB 6 + SiB n ) containing SiB n phase, shows the lowest entropy (~32 J/mol*K) in this system at 1100 K.

Siliceous manganese ore, associated with the banded iron formation occurs in large volume in northern Odisha, India. It is a sub-grade ore containing 21% Mn, 60% SiO 2 and 3% Fe, hence do not find any use and considered as waste. Such ore does not respond to any physical beneficiation techniques because of intricate microstructure and poor liberation of Mn-phase. It could only be up-graded to 32% Mn with 36% yield and 52% recovery by processing it through mineral separator followed by WHIMS. Siliceous manganese ore along with calcite and coke in appropriate ratio, when charged to a plasma reactor, a product with slag metal ratio of 2.5:1 was obtained within a period of 10 min. Electron probe micro-analysis of the metal confirmed it to be ferrosilicomanganese while the slag constitute of tricalcium silicate (C3S) with around 5% Mn in adsorbed state.

The hot deformation behaviors of an aged Inconel 718 superalloy are investigated by isothermal compression experiments at four strain rates and five deformation temperatures on a Gleeble-3500 thermo-mechanical simulator. The experimental results show that the true stresses are obviously affected by strain rate and deformation temperature. The true stress increases rapidly at the beginning of hot compressive deformation, which ascribes to the intense work hardening. The true stresses at high deformation temperatures are lower than those at lower deformation temperatures. The dynamic softening induced by DRX is weak at a relatively low deformation temperature. A strain-compensated Arrhenius-type constitutive equation linked with true stress, strain rate and deformation temperature is developed for the studied superalloy. The material constants (α\alpha , n, Q and A ) in the developed model are expressed as the functions of true strain. The flow stresses calculated by the developed constitutive equation are nicely consistent with the experimental ones, which confirms that the developed constitutive equation can accurately describe the hot deformation behaviors of the studied superalloy.

The chromium was deposited on the surface of 0.45 C medium carbon steel by high current pulsed electron beam (HCPEB) alloying treatment to obtain a high quality alloying layer. The microstructure of the alloying layer was studied by X-ray diffraction, optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy. The hardness of the surface was measured by Vickers durometer. The corrosion resistance of samples before and after HCPEB irradiation was also measured by an electrochemical workstation. The results showed that the alloying layer with a dept of about 4–9 μm on the surface was formed after HCPEB alloying treatment. TEM results revealed that the Cr element is dissolved on the surface and alloyed with C element in the substrate to form Cr 23 C 6 enhanced particles. The microhardness and corrosion resistance of the medium carbon steel subjected to a HCPEB alloying processing were remarkably improved compared with the original one.

The deformation behavior of 49MnVS3 non-quenched and tempered steel was studied using isothermal compression tests at the temperature range of 750–1000  °C and the strain rate range of 0.1–50 s −1 on a Gleeble-3500 thermal mechanical simulator. The results indicated that the flow stress increases significantly with decreasing temperature and increasing strain rate. Under the whole deformation conditions, the dependence of flow stress on deformation temperature and strain rate was analyzed by hyperbolic sine equation. Besides, the hot deformation activation energy and stress exponent were calculated to be 323.56 kJ/mol and 6.99, respectively. In addition, the processing map based on dynamic material model was established, and the optimum processing condition of the 49MnVS3 non-quenched and tempered steel can be determined to be at the temperature range of 809–850 °C and strain rate of 36.6 s −1 –50 s −1 .

Constitutive analysis for elevated temperature flow behavior of BFe10-1-2 alloy was carried out by using experimental stress–strain data from isothermal hot compression tests on a Gleeble-3800 thermo-mechanical simulator, in a wide of temperature range of 1,023–1,273 K, and strain rate range of 0.001–10 s −1 . A constitutive equation based on double multiple nonlinear regression (DMNR) was proposed considering the independent effects of strain, strain rate, temperature and their interrelation. The predicted flow stress data obtained from the developed equation based on DMNR was compared with the experimental data. Correlation coefficient ( R ), average absolute relative error ( AARE ) and relative errors were introduced to verify the validity of the developed constitutive equation. The results showed that the developed constitutive equation based on DMNR could predict flow stress of BFe10-1-2 alloy with good correlation and generalization.

The oxidation tests of Ferritic Steel T22 exposed to supercritical water (SCW) at 540–620°C and 25 MPa was performed for up to 1000 h. The oxidation rate increased with increasing exposure temperature and time. Oxide films formed on T22 have a double-layered structure with an outer layer consisting of iron oxide and an inner layer consisting of spinel oxide. Numerous pores on the surface can be observed at the initial oxidation stage while they seemed to heal with increasing exposure time at 620°C. Cracks occurred along grain boundaries in the oxide scale when T22 exposed for 200 h at 620°C. The influence of time and temperature on the oxidation of Ferritic Steel T22 was discussed.

A fully coupled thermo-mechanical model is established to simulate the temperature variations and the material deformations in friction stir welding (FSW) of Ti-6Al-4V. The extracted data are used for further simulation on microstructural evolutions. A multi scale model, which consists of the grain growth model in grain cluster scale and the phase transformation model in one grain scale, is proposed. The nuclei of α and β phases, the recrystallizations and the grain growths are systematically investigated. Comparisons with experimental data and experimental observations can validate the newly proposed microstructural evolution model for Ti-6Al-4V. Results indicate that the volume fractions of α and β phases can be directly determined by the cooling rates in FSW process. With the increase of the rotating speed, the volume fraction of α phase is increased and β phase decreased due to the increase of welding temperature. With the decrease of the translational speed, the volume fraction of α phase gets bigger and β phase smaller. The acicular α grain can be generated on the β grain boundaries and grows along <1 1 0> direction on β substrate. The average length of α grain can be increased with longer cooling time and decreased with lower rotating speed or higher translational speed.

The partition behavior of alloying elements between the γ’ and γ phases in Nickel-based alloys was investigated by using infinite dilution activity coefficient and activity interaction parameter. The results showed that the preferential partition behavior of elements in the γ’ and γ phases is related to its infinite dilution activity coefficient (lnγi0\ln \gamma _i^0). When lnγi0≪0\ln \gamma _i^0 \ll 0, the element i has a strong tendency to partition in the γ’ phase; When lnγi0\ln \gamma _i^0 approaches to zero, the element i has preferentially partition to the matrix γ phase. In addition, the partition behavior of element i in the γ’ and γ phases is also affected by the third element j in Nickel-based alloys, and this effect can be distinguished by the sign of the second-order activity interaction parameter ρiij\rho _i^{ij}.

Heating procedures dramatically influence the physical-mechanical properties of rock. In this paper, via both numerical simulation and laboratory experiments, we examine the influence of constant temperature period (CTP, from 0.5 to 5 h) and predetermined temperature (PDT, from room temperature to 1,000℃) on the tensile mechanical properties of the Qinling granite, China. Results indicate that: CTP has a significant impact on the tensile mechanical properties of granite. For different PDTs, the density, longitudinal wave velocity (LWV) and tensile strength (TS) of granite decrease with increasing CTP. When CTP reaches the constant temperature turning-point (CTT), heating has fully affected the granite samples. The variation in LWV and TS versus temperature can be divided into four stages: 25–200℃, 200–600℃, 600–800℃ and 800–1,000℃. LWV and TS are negatively related to temperature and are more sensitive to temperature at higher PDTs. In addition, TS is more sensitive to temperature than LWV when PDT increases. The effects of CTP and PDT on LWV are similar to that of TS. Since the measurement of LWV is lossless, researchers can safely determine the appropriate CTP or CTT for any PDT and predict the tensile mechanical properties of rock by LWV analysis.

Three kinds of welding filler wires, named ER5356, ER5087 and ER4043, were used to joint 12 mm thick Al-Zn-Mg alloy plate by the pulsed MIG(P-MIG) welding. The microstructure and mechanical properties of the joints were analyzed and compared. The results showed that the average tensile strengths of the joints filled with ER5356, ER5087 and ER4043 were 294 MPa, 313 MPa and 237 MPa, respectively, and the average elongations were 7.9%, 7.6% and 1.6%, respectively. All the joints’s fracture locations were near the fusion boundary. The microhardness test showed that the locations of the lowest hardness were all in the center of cross section. The results revealed that the weld filler by ER5087 was consist of more columnar crystals of larger grain size, while the weld filled by ER5356 was consist of more equiaxed grains of smaller grain size. The microstructure of the weld by ER4043 was typical eutectic dendrites structure.

6082-T6 aluminum alloy plate with thickness of 42mm was butt welded by friction stir welding (FSW) from two sides. The microstructures of the joints exhibited different grain sizes because of unequal frictional heating and plastic flow during FSW process. The transition from the heat affected zone (HAZ) to the nugget zone (NZ) in thermos-mechanical affected zone of advancing side (AS-TMAZ) was more sudden than thermos-mechanical affected zone of retreating side (RS-TMAZ). Kissing bond (KB) defect throughout the entire FSW joint was displayed both at the grain boundary and in the interior of the grain with semi-continuous bands. KB had no direct effect on tensile properties. Vickers hardness of the FSW joint was lower than the BM because its high heat input, dissolved and coarsened precipitates and little to the grain size after FSW. Hardness distribution of double-sided welding joint showed X-shaped area softening characteristics, that is to say the lowest hardness was the junction of two welding joint of NZ and the junction of TMAZ and HAZ. The tensile fracture position occurred in the lowest hardness region of the FSW joint, and it did not occur in the KB defect position.

High-temperature oxidation behaviour of Mo-40Ti-30Si (at.%) alloy was investigated in the temperature regime of 900-1300 ∘ C in air. Isothermal weight change data recorded up to 100 h of exposure revealed parabolic weight gain kinetics at all the tested temperatures. The protective oxide scale composed with SiO 2 (silica) and TiO 2 (titania) forming a duplex oxide microstructure consisting of TiO 2 particles embedded in the continuous SiO 2 matrix. The oxide scale showed parabolic growth kinetics, and the activation energies for the scale growth were found to be 72.2 kJ/mol in 900-1200 ∘ C and 324.9 kJ/mol in 1200-1300 ∘ C. The kinetics of the protective scale growth on the alloy surface was mainly controlled by the growth of the silica film and the inward diffusion of oxygen through the duplex oxide layer.

The paper presents results of calorimetric investigation of the Bi-Cu-Sn system by means of differential scanning calorimetry (DSC) at the temperature interval 25-1250 ∘ C, Values of liquidus, solidus and invariant reactions temperatures, as well as melting enthalpies of the selected alloys were determined. Microstructure investigation of the alloys were performed by the use of a scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS).

To achieve reuse of converter slag, the influence of the P 2 O 5 content on the component activity of dephosphorization slag, the basicity of the slag, and the phosphorus content in liquid steel were studied and the influence of temperature on the end phosphorus content in liquid steel was analyzed. The results show that the slag remaining in the last heat still exhibited strong dephosphorization ability. Six heats of industrial basic oxygen furnace trials with a 100t-scale top–bottom combined blown converter were carried out using slag-remaining technology. The phases of dephosphorization slag were analyzed by scanning electron microscopy– energy dispersive X-ray spectroscopy and X-ray diffraction. The decomposition reaction of RO phase (a solid-solution composed of some divalent metal oxides, such as FeO, MgO, MnO, CaO, etc.) was relatively complete in slag with a high CaO/SiO 2 ratio but was not complete in the slag with a low CaO/SiO 2 ratio. Euhedral crystals of 2CaO· SiO 2 with certain amount of 3CaO· P 2 O 5 were formed, resulting in a solid-solution phase of 2CaO· SiO 2 –3CaO· P 2 O 5 . The liquid phase was present in greater amount and was mainly composed of calcium ferrite. The enrichment of SiO 2 and P 2 O 5 was easier with increasing recycling times of the converter slag. To maintain a higher efficiency of dephosphorization, the P 2 O 5 content in the slag should be maintained below 3% and the CaO/SiO 2 ratio of slag should be maintained above 3.

In order to improve joint integrity and reduce the amount of intermetallic compounds (IMCs), 6061-T6 Al and AZ31B Mg alloys were successfully joined by stationary shoulder friction stir welding (SSFSW). The stationary shoulder effectively enhanced the joint surface integrity and reduced the thickness reduction of the Al/Mg joint. The elimination of pin adhesion was beneficial to increasing material transfer and then improving interfacial joining length of Al/Mg joint. Extremely thin IMCs layer could be achieved because of the heat sink induced by the stationary shoulder. The maximum tensile strength of the Al/ Mg joint reached 137 MPa at a welding speed of 60 mm/min, rotating velocity of 1000 rpm and offset to Mg sheet of 0.3 mm, which was 130% higher than that of conventional joint. SSFSW is feasible and has the potential to join dissimilar materials with the formation of IMCs, such as Al/Mg alloys, Al/copper alloys, Al/titanium alloys and so on.

The microstructure evolution of U-Nb alloys during solidification and consequent cooling process was simulated using a cellular automaton (CA) model. By using this model, ϒ phase precipitation and monotectoid decomposition were simulated, and dendrite morphology of ϒ phase, Nb microsegregation and kinetics of monotectoid decomposition were obtained. To validate the model, an ingot of U-5.5Nb (wt.%) was produced and temperature measuring experiment was carried out. As-cast microstructure at different position taken from the ingot was investigated by using optical microscope and SEM. The effect of cooling rate on ϒ phase precipitation and monotectoid decomposition of U-Nb alloys was also studied. The simulated results were compared with the experimental results and the capability of the model for quantitatively predicting the microstructure evolution of U-Nb alloys during solidification and consequent cooling process was assessed.

MgTiO 3 powder was directly added into molten steel at 1873K, and its effect on inclusion characteristics was studied by a scanning electron microscope and an energy dispersive spectrometer. Thermodynamic calculation indicates that MgTiO 3 is unstable in molten steel and may decompose into [Ti], [O] and MgO. However, only Ti-bearing inclusions were observed in the treated sample, and Mg-bearing inclusions were absent. This can be explained by the features of wettability and stability for MgO. Compared with a Non-treated sample, both oxide and coarse MnS in treated sample were refined. For the oxide, this originates from the formation of Ti-bearing inclusion. For coarse MnS, this may be due to the fact that Ti can aggravate S segregation. Besides, this aggravation makes coarse MnS less globular. After etching, it was found that in the treated sample, Ti-bearing inclusion can induce the nucleation of intragranular acicular ferrites. This appearance was totally different from that of Non-treated sample, and indicates the effectiveness of external adding method in oxide metallurgy.

The cutting force, the friction coefficient of the rake face, and the flank wear of functional gradient cemented carbide (FGCC) cutting tools prepared by microwave heating and nitriding sintering were tested by turning test and compared with those of a conventional cemented carbide cutting tool. The results show that the cutting force, the friction coefficient of the rake face, and the wear of the GFCC cutting tool are lower than those of the conventional cutting tool with the same composition. Additionally, the effects of cutting speed on cutting force and tool wear were studied. Furthermore, the failure mechanism in the cutting process, the heat distribution of the second derformation zone and the resistant to the generation and extend of tool surface micro-cracks were analyzed. The friction and wear mechanism of the FGCC tool was found to be affected by the gradient distribution of the tool surface composition.

The cast nickel-base MAR-M247 superalloy has been widely used for high-temperature components. In this work, the creep behaviour of two alternates of MAR-M247 superalloy with different grain size processed at different temperatures of casting are compared. Under the creep testing conditions used in this study, only negligible differences of creep behaviour of the alternate alloys were found and the evaluated creep characteristics correspond to the power-law or dislocation creep. The microstructure of the alloys consists of a 𝛾 matrix with a eutectic, 𝛾' strengthening cubic precipitates, and M 6 C and M 23 C 6 carbides. Increasing the temperature induces the dissolution of some M 23 C 6 carbides. Fractures of both variants of alloys exhibit a more ductile character at higher temperatures, while at lower temperature a mixture of brittle and ductile fracture modes was observed, which changes the creep fracture ductility.

In this work, the substrate, NiCr coating, Al 2 O 3 coating with NiCr undercoating and Al 2 O 3 coating were tested by an impact indentation device equipped with an acoustic emission (AE) detection equipment. The surface morphology, dimension, cross-sectional image, 3D topography of indention and bonding strength of coatings were analyzed. The failure mechanism and AE signal characteristics of the coatings under impact were studied. The results demonstrate that the failure mode of NiCr coating was dominated by interface cracking, and that of Al 2 O 3 coating is fracture and accompanied by a small amount of interface cracking, while Al 2 O 3 coating with NiCr undercoating possesses common characteristics of the first two. The energy counting and wave voltage of AE signal were more sensitive to the bonding strength of coating in the impact process, which can be used to characterize the bonding strength of coating.

A beam blank is ideal for H-beam production, but there are more defects in/on beam blanks than other common blanks. The study of the H-beam blank quality assurance system has great significance for production to determine the key factors causing defects and optimise the casting process parameters. Experimental analysis and numerical simulation, based on an actual production process, were used as research methods. The former was used to test and analyse the cracks, inclusions, and the flux in the mould to determine the preliminary factors causing defects in a beam blank. The latter was used to simulate the flow and temperature fields and the movement of inclusions to determine the key factor leading to defects and to optimize the casting process parameters. Online implementation of the recommendations of this project was developed, which proved that it is very useful and efficient to control surface cracks on the web and enhance cleanliness of an H-beam blank.

The rhodium 0,5 μm thick layer was deposited on pure nickel and CMSX 4 Ni-based superalloy using the electroplating method. The rhodium coated substrates were aluminized by the CVD method. Oxidation resistance of nonmodified and rhodium modified coatings deposited both on nickel and CMSX 4 superalloy was compared. The triple-layer structure of rhodium modified coatings deposited on pure nickel was found. The β -(Ni,Rh)Al, rhodium doped γ' -Ni 3 Al and rhodium doped γ -Ni(Al) phases were the main components of the coatings on pure nickel. Two layers – additive and interdiffusion ones were identified in coatings deposited on CMSX 4 superalloy. TEM, SEM and XRD analysis revealed that β -(Ni,Rh)Al phase was the main component of the additive layer. Moreover Topologically Closed-Pack σ phases containing refractory elements in the β -(Ni,Rh)Al matrix of the interdiffusion layer were found. The rhodium modified aluminide coatings have better oxidation resistance than the nonmodified ones both on the pure nickel and CMSX 4 superalloy.

Niobium has the potential as an inhibitor forming element in grain oriented silicon steel. The grain oriented silicon steels with different Nb contents (0.028 wt% and 0.052 wt%) were prepared, and the effect of Nb content on the evolution of precipitates, microstructure and texture were investigated by the various analysis methods and thermodynamic calculations. The results show that the smaller size and larger number density of precipitates were obtained in the sample with low Nb steel after hot rolling. In the process of normalization, Nb(C, N) are more inclined to precipitate along the dislocations caused by hot rolling, contributing to finer and more dispersed precipitates in normalized bands. The finer and more dispersed precipitates in 0.028% Nb containing silicon steel perform a stronger pinning force during whole heat treatment processes, resulting in the smaller grain size and higher intensity of Goss texture in the specimen containing 0.028%Nb. After normalization, the intensities of Goss texture in both steels decrease.

Atmospheric plasma spraying (APS) technique is employed to prepare Fe-based amorphous coatings on T91 steel substrate under various arc powers of 30 kW, 35 kW and 40kW. The morphology and microstructure of both Fe-based powders and amorphous coatings are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). In addition, the wear resistance and high-temperature oxidation resistance of the plasma-sprayed coatings at various arc powers are studied. It is found that with increasing the arc power, the content of the porosity and the amorphous phase in the coatings declines. Specifically, under 30 kW, 35 kW and 40 kW arc power, the porosity of the coatings is 7.96%, 6.13% and 5.75%. Correspondingly, the relative content of amorphous phase from the coatings is measured to be 96.07% (mass fraction), 73.89% and 65.54%. Moreover, under 40 kW arc power, it gives the coating the highest micro-hardness having more compact microstructure and more dispersive α -Fe grains. Besides, the coatings fabricated at high arc power exhibit less wear induced weight loss and less weight gain from high-temperature oxidation comparing with those fabricated at lower arc power.

This elementary work aims to address agglomeration and non-uniform dispersion of reinforcement particles in stir casting using Al6061 alloy (AA 6061) as a matrix and Aluminium oxide (Al 2 O 3 ) as reinforcement particles. A novel combined feeding method of Encapsulate feeding technique & Two Step Stir Casting was developed & attempted to produce good quality composites by varying weight fractions of Aluminium Oxide (0 to 5 wt.%). The wetting agent Mg (2 wt.%) added in all castings to ensure better binding between ceramics and matrix. The SEM photomicrograph ensures homogenous dispersion of reinforcement particles by combined feeding method. The thermal properties of produced good quality composites are enhanced with increase in Aluminium Oxide (Al 2 O 3 ) from 0 to 5 wt.%.

The changes that occur in the microstructure of crystalline and amorphous Cu-P-Sn-Ni filler metals during the heating process were studied by high-temperature microscopy, and the composition of solders at certain temperatures were analyzed by scanning electron microscopy and X-ray diffraction. The amorphous solder was observed to transform from amorphic to crystalline during the process of heating and distinct surface morphology changes were apparent, while the internal structure of the crystalline brazing filler metal was found to be relatively stable. During the heating process, the amorphous brazing filler metal formed a ϒ -Cu solid solution with a small amount of Cu 3 P compounds, Cu 88 Sn 22 and (Cu, Ni) 3 P phase compounds, ultimately forming the Cu 88 Sn 22 + Ni 12 P 5 + (Cu, Ni) 3 P 3 three-element eutectic structure.

Friction stir welding (FSW) can achieve a sound welding joint, but its residual stress and distortion cannot be avoided due to the non-uniformity of temperature distribution during welding. Stationary shoulder friction stir welding (SSFSW) was employed to butt weld 6005A-T6 aluminum alloy plates. The effects of welding speeds ranging from 200 mm/min to 600 mm/min on residual stress and distortion were investigated in detail. A thermo-mechanical model was utilized to compare the residual stress distribution between conventional FSW and SSFSW. SSFSW was beneficial to decreasing the peak temperature of stir zone (SZ) and then obtaining a narrower SZ. The peak residual stress produced by SSFSW was 50% lower than that by conventional FSW and a narrower tensile stress region was attained by SSFSW. Moreover, the stationary shoulder applied a function of synchronous rolling during the welding, which controlled the distortion effectively.

In order to reduce the air gap between ingot and mould in the electroslag remelting withdrawal (ESRW) process, the taper of the mould should be consistent with the ingot shrinkage.Athree-dimensional mathematical model was developed to describe the interaction of multiple-physical fields (Joule heat, electromagnetic field, velocity field, and temperature field) and ingot shrinkage during the ESRW process. The variations of material thermal and mechanical properties, as well as the yield function with temperature, were considered. The shrinkage behavior of 9Cr3Mo roller in the ESRW process was simulated using the sequential coupling method. A good agreement between the calculated value and the measured valuewas obtained in the temperature field and stress field. Numerical results showed that maximum values of current density, Joule heat, and electromagnetic forcewere at the electrode corner of the slag bath. The direction of the magnetic flux density was tangential to the slag bath and had a clockwise rotation. There were two pairs of vortices and two high temperature zones in the slag bath. The shrinkage displacement was obtained through thermal-stress analysis. As the distance from the mould outlet decreases, the shrinkage displacement of ingot increases. As for the electroslag remelting withdrawal process for 9Cr3Mo roller, the variation of the shrinkage displacement from the slag/metal interface to the mould outlet was 0.0028 m. The maximum shrinkage displacement is at the mould outlet, and the value was 0.0089 m.

Mo-Ni-B-Al as-cast alloys containing 35.5-58.7 wt% Mo, 23.0-57.6 wt% Ni, 3.3-5.2 wt% B, and 2.2-13.5 wt% Al were synthesized by Self-Propagating High-Temperature Synthesis (SHS) using a mixture of MoO3, NiO, B2O3 and Al powders in order to obtain low-cost Mo2 NiB2 containing hard materials. The first series of experiments were performed using 1.05 times the stoichiometric amount of Al. In the second series of experiments, FactSage thermochemical modeling software was used to minimize Al increasing the Mo2NiB2 formation in the as-cast alloys. The products were characterized by using atomic absorption spectrometry (AAS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and micro-hardness techniques.

Plasma-sprayed cast iron splats were deposited onto polished aluminum substrates preheated to different temperatures ranging from 25°C to 250°C. The morphology of single splat was observed by a field emission scanning electron microscope. Quantitative characterization methods, including fractal dimension (FD) and circularity analyses of the splat profile, were employed to identify the difference in morphology of the splats with the change of the substrate temperature. The results showed that the substrate temperature has a significant effect on the spreading of molten droplets and the morphology of resultant splats through changing the solidification rate of the droplets. With the increment of substrate temperature, the homogeneous and sufficient spreading of the droplets resulted from low solidification rate reduces the splashing of the droplets. In addition, the evaporation of adsorbed moisture on the substrate improves the wettability between the spreading droplet and the substrate, then benefits the homogeneous spreading of the molten droplet. As a result, a distinct decline in the FD value was observed. It was also suggested that the FD analysis could be used to characterize the morphology of the splat more effectively while the circularity method was heavily dependent on the area of the splat.

The true strain data and true stress data are obtained from the isothermal compression tests under a wide range of strain rates (0.1–20 s −1 ) and temperatures (933–1,133 K) over the Gleeble-3500 thermomechanical simulator. The data are employed to generate the constitutive equations according to four constitutive models, respectively, the strain-compensated Arrhenius-type model, the modified Zerilli–Armstrong (ZA) model, the modified Johnson–Cook (JC) model and the JC model. In the meanwhile, a comparative research was made over the capacities of these four models and hence to represent the elevated temperature flow behavior of TA2. Besides, a comparison of the accuracy of the predictions of average absolute relative error, correlation coefficient ( R ) and the deformation behavior was made to test the sustainability level of these four models. It is shown from these results that the JC model is not suitable for the description of flow behavior of TA2 alloy in α + β phase domain, while the predicted values of modified JC model, modified ZA model and the strain-compensated Arrhenius-type model could be consistent well with the experimental values except under some deformation conditions. Moreover, the strain-compensated Arrhenius-type model can be also used to track the deformation behavior more precisely in comparison with other models.

In microwave drying technology, research into the dynamic absorbing properties of the powder is indispensable. In this study, the reflection loss coefficient of paracetamol powder under different temperature, water content, and thickness was calculated based on the principle of electromagnetic wave transmission. The results show that the absorption performance of powder fluctuates dynamically with a series of absorption peaks, and the position of the absorption peak shifts toward the smaller thickness direction as the water content increases or the temperature rises. Because of the influence of the powder thickness on absorbing efficiency, the powder thickness should be adjusted in real time to increase drying efficiency. This study provides the thickness range for which the absorption performance of paracetamol powder under different conditions is over 99%. This study is of great significance for understanding the drying mechanism and optimizing process parameters for microwave drying of pharmaceutical powder.

In this study, the blast furnace slag of the Baotou Steel and Iron Company was used as the main raw material to prepare glass ceramics with diopside as the main crystal phase. The composition of the parent glass was designed by thermodynamic calculations with FactSage software. Small amounts of the nucleation agent Cr 2 O 3 were then added to the parent glass to induce crystallization. Differential thermal analysis was used to determine the nucleation and crystallization temperatures of the glasses, and scanning electron microscopy and X-ray diffraction were adopted to determine the microstructures and phase compositions of the glasses after heat treatment, respectively. The results showed that glass ceramics of the diopside phase can be prepared with up to 73 wt% blast furnace slag when 1.44–1.91 wt% Cr 2 O 3 is added, and the ceramics have uniform compact grains and a high bending strength of about 84.6–101.7 MPa. In addition, the mechanical properties are better than those of natural marble and granite. These results provide basic information and a scientific basis for industrial production of diopside glass ceramics using molten blast furnace slag as the main raw material.

In order to explore the influence of unburned pulverized coal on gasification reaction of coke in blast furnace, kinetic rules of gasification reaction between CO 2 and coke powder adding pulverized coals with different volatiles were studied by thermogravimetric analysis. The results showed that weight-loss ratio of samples reacted with CO 2 increased after adding pulverized coal, and the weight-loss ratio rose with the increase of coal’s addition. When the content of pulverized coal was up to 50%, the weight-loss ratio of the sample which adding pulverized coal with high volatile was higher under the same temperature. The activation energy about C-CO 2 gasification reaction of samples reduced observably after adding pulverized coal. The activation energy of samples had a largest decrease with 83.408 kJ mol− 1 at the range of 1223 K~1373 K and it was 28.97 kJ mol −1 at the range of 1373 K~1523 K. The addition of pulverized coal with high volatile can reduce the reaction activation energy of samples more effectively. In the soft melting zone, the gasification reaction model of coke blocks attached the unburned pulverized coal was up to unreacted core model and porous volume-reacted model jointly.

We clarified the effect of post weld heat treatment (PWHT) conditions on the toughness and creep rupture strength of modified 9Cr–1Mo steel weldments used for high temperature components of ultra-supercritical power plants. Fracture appearance transition temperature (FATT) decreased as PWHT temperature increased, and for all of the weld metals of tungsten inert gas welding, submerged arc welding and shielded metal arc welding, FATTs were lower than 293 K when the PWHT temperature was higher than 1,008 K. In contrast, in the uniaxial creep test with a loaded stress of 108 MPa, the creep rupture strength of the specimen on which PWHT was carried out for a holding time of 7.2 ks was significantly decreased when the PWHT temperature was more than 1,033 K. Therefore, the appropriate PWHT temperature range to maintain the toughness and creep fracture strength was 1,008 K ≤  T  ≤ 1,033 K.

Most traditional mold fluxes are Newtonian fluids, and their constant viscosity has certain limitations in continuous casting. A new non-Newtonian fluid mold flux with shear-thinning behavior, i.e ., a mold flux with a relatively high viscosity at lower shear rates and a relatively low viscosity at higher shear rates, is required to satisfy the mold-flux performance requirements for high-speed continuous casting. The addition of a certain amount of B 2 O 3 to a CaO–SiO 2 –Na 2 O-based mold flux can result in a shear-thinning property. To obtain an improved understanding of the mechanism of this characteristic, a molecular-dynamics simulation method was used to study the microstructural changes of the mold flux. Structural changes of mold-flux samples were analyzed and verified by Raman spectroscopy. The results of the two methods were almost the same, both resulted from the addition of B 2 O 3 and changed the microstructure and degree of polymerization of the mold flux, which resulted in the shear-thinning property of the mold flux. This non-Newtonian fluid mold flux was used in square-billet casting tests, and the quality of the slab was improved effectively.

By laboratory slag/steel reaction equilibrim experiments, the viriation of oxygen content, inclusion compositions and inclusion sizes were studied. The effect of acid slag treatment on the transition mechanisms of D-type inclusions and the precipitation of TiN inclusions in GCr15 bearing steel were explored. The obtained results showed that the dominant inclusions in steel were plastic and smaller Al 2 O 3 -SiO 2 -MnO. The melting point were lower than 1400°C treated by the acid refining slag of 35.1%CaO-15%Al 2 O 3 -43.9%SiO 2 -6%MgO and there was no TiN found. The evolution of MgO·Al 2 O 3 inclusions is: MgO·Al 2 O 3 → MgO·Al 2 O 3 ·SiO 2 ·MnO → Al 2 O 3 ·SiO 2 ·MnO. Mg and Al from MgO·Al 2 O 3 inclusions were displaced by [Si] and [Mn] in steel liquid , and formation of plastic Al 2 O 3 -SiO 2 -MnO inclusions finally, whose compositions distribution were uniform. Mg and Si, Mn were complementary in inclusions as to the spatial distribution.

The amount of dust produced from the blast furnace is very large, and this paper proposed a new method for comprehensive utilization of blast furnace dust. Firstly, cold bonded agglomerates directly put into the iron groove were made by blast furnace dust. The cold bonded agglomerates were reduced and melted by the energy of molten iron, and the valuable elements such as Fe reduced into molten iron and zinc existed in rich-Zn dust in the cold bonded agglomerates could be recovered. In order to simulate this process, the reduction behavior of cold bonded agglomerate in the iron bath was studied, and the reduction mechanism were analyzed by Factsage calculation and SEM-EDS. The results showed that: in the slag phase, there were small metallic iron particles dispersed and hard to gather. The main reason for this phenomenon is due to the hindrance role of the carbon residue in the agglomerates, and the problem could be solved through adding magnetite concentrate in cold bonded agglomerates.

Crystalline cerium-zirconate (CZ) powders were synthesized via solution-assisted combustion synthesis route and calcined at 850°C for 8 h to obtain coarse crystalline powders. SEM (scanning electron microscopy) characterization studies were done to evaluate the morphology of the powders. XRD analysis of the resulting powder confirmed the presence of crystalline α-Ce 2 Zr 2 O 7 along with a Ce 2 Zr 2 O 8 phase having a disordered fluorite cubic lattice. Phase composition, lattice parameters, and the atomic positions were also investigated. Refinement of XRD data was done to quantify the amount of α-Ce 2 Zr 2 O 7 and Ce 2 Zr 2 O 8 phases. Ni-base superalloy Inconel 625 was chosen as the coating substrate, and the powders were coated using an air plasma spraying (APS). A thermally grown oxide (TGO)/Al 2 O 3 layer was observed owing to the high temperature of the substrate as well as the diffusion of bond coat material into the substrate. Coated samples were characterized by SEM to study the surface morphology, coating thickness, and interface microstructures. The thickness of the coated sample was found to be 400 μm. Thermal cycling test of the coated sample was carried out at 750°C for 50 h to evaluate the thermal shock resistance of the coating as well as the spalling behavior of the coating. Preliminary oxidation tests were carried out for 50 h at 750°C to evaluate the oxide growth by measuring weight gain of the oxide layers formed. Oxide growth signifies the gradual increment of layers over a period with a parabolic rate constant of about K p = 1.18 × 10 –3 mg 2 cm –4 h –1 .

Combustion process of bituminous coal, steam coal, anthracite (AC) and semi-coke were investigated through thermogravimetric analysis method and influence of metamorphic grade as well as heating rate on combustion characteristics were analyzed. Results show that combustion performance could not be represented by single combustion characteristic parameter. Through analysis of comprehensive combustion characteristic indexes, with increase of metamorphic grade combustion performance of coal is lowered, and combustion performance of semi-coke and AC are close to each other. With increase of heating rate, combustion curves move into high temperature region and comprehensive combustion characteristic indexes are increased, which show that the combustion performance is improved. Random pore model (RPM), unreacted shrinking core model (URCM) and volume model were used to calculate kinetic parameters of combustion process. Results show that RPM has the best performance to represent combustion process of the four samples and through calculation by RPM kinetic energy of combustion process for all samples are between 43.08 and 99.43 kJ/mol, and there is compensation effect during combustion process.

The present study compares the mechanical properties and electrochemical behaviour of austenitic (AISI 316 L) stainless steel compacted at different pressures (200, 400 and 600 MPa), which are conventionally sintered at supersolidus temperature of 1,400°C. As expected, increase in compaction pressure (from 200 MPa) to 600 MPa has shown decreased shrinkage (from 7.3% to 4.2% radial and 5.5% to 3.4% axial, respectively) and increased densification (up to ~92%). Their electrochemical behaviour was investigated in 0.1 N H 2 SO 4 solution by potentiodynamic polarization and electrochemical impedance spectroscopy. The mechanical properties (such as yield-, tensile- and transverse rupture strength) and electrochemical behaviour with pressure have been correlated with densification response and microstructure (pore type, volume and morphology). Highest densification (~92% theoretical) achieved at 600 MPa (compaction pressure) and 1,400°C (sintering temperature) resulted in excellent combination of tensile strength and ductility (456 ± 40 MPa and 25 ± 1.1% respectively), while showing lowest corrosion rate (0.1 mmpy or 4.7 mpy) due to the presence of isolated porosity in the sintered samples.

Cu-doped Cr 2 O 3 thin films were deposited onto glass substrate by the sol–gel dip-coating (SGDC) process using dopant values of 0, 3, 6, 9 and 12%. The Chromium (III) Nitrate Nonahydrate [Cr(NO 3 ) 3 ·9H 2 O] was used as a Cr source, whilst for the dopant, the corresponding nitrate (Cu(NO 3 ) 2 ) was used. The crystal structure, as well as the optical and electrical properties were examined. XRD data showed that the films with a high degree of crystallinity were rhombohedral Cr 2 O 3 phase. The crystallite size reduces with increase in Cu doping proportion. The AFM results indicate a decrease in the surface roughness of the doped Cr 2 O 3 : Cu thin films. The UV-Vis spectra of the Cu doped-Cr 2 O 3 films showed high transparency in the visible region. The optical band gap of Cr 2 O 3 thin films decreases with increasing in Cu doping rate. The Nyquist plot shows that the equivalent circuit of Cu doped-Cr 2 O 3 films is a parallel circuit R p C p . As the concentration of Cu increases, Resistance R P regresses while capacitance C p increases.

To figure out the reason causing ladle nozzle clogging during a continuous casting process (or CC for short) for the silicon steel and get away to solve it, this paper studied the theoretical calculation of flow rates during casting, inclusions around the slide gate where ladle nozzle clogging happened, and Ca-treatment on refining units for producing the silicon steel. The results showed that: The bigger diameter of a nozzle or less nozzle clogging can guarantee an enough flow rate for reaching the target casting speed. Ladle nozzle clogging can be predicted by analyzing the percentage of a slide gate being opened. Al 2 O 3 and its composite inclusions were the main ones which cause the nozzle clogging during the CC process of the silicon steel. Ca-treatment could transform those high melting point inclusions into C12A7 by adding Si-Ca wires and prevent the ladle nozzle clogging of the silicon steel.

Thermodynamic analysis was performed to obtain the relation between the carbon content at the BOF endpoint and the dissolved oxygen content in liquid steel and the (FeO + MnO) content in the slag with the help of thermodynamic calculation software FactSage. It finds that both the [O] and (FeO + MnO) content increase with decreasing the carbon content at the BOF endpoint and the increasing rate is larger when the carbon content is lower. In addition, in the case of the higher temperature at the BOF endpoint the [O] in liquid steel increase and the (FeO + MnO) in the slag increase as well. The consumption of O 2 for decarbonization at the BOF endpoint is much more than that in RH degasser since the majority of the blowing O 2 at the BOF endpoint will produce FeO into the slag, thus it increase the metal loss and deteriorate the steel cleanness during the consequent refining process. As a result, the carbon content at the BOF endpoint should be properly increased within the RH decarbonization ability. At last, industrial trials were carried out and confirmed that total oxygen consumption decrease obviously and the (FeO + MnO) of final BOF slag decline as well with increasing carbon content at BOF endpoint from 0.042% to 0.081%. In addition, it almost does not slow down the RH process and the carbon content in final steel all met the demand of the ultra-low carbon steel. In addition, mechanical properties of IF steel with higher carbon content at the endpoint of BOF are almost all more superior to those of heat with lower carbon content at BOF endpoint.

In the present work, the prediction of residual stresses and distortion due to GTA welding process, a Finite Element (FE)Method has been developed and applied. Stainless steel plate of 3mm thickness is taken for the analysis. The prediction of residual stresses and distortion is performed by thermal and mechanical analysis that is sequentially coupled. The thermal analysis and mechanical analysis of the plate subjected to heat source movement have been studied consecutively. The FE analysis is performed in ANSYS software. In transient thermal analysis, Gaussian distribution model has been used for heat input of the arc. During modeling, the physical and mechanical properties that depend on temperature are considered. The heat transfer losses through all the three mechanisms are incorporated. For validating the FE simulated analysis, an experiment is conducted. The predicted thermal histories are very close agreement with measured thermocouple readings. After validation of thermal analysis results, the transient thermal histories are used as input for further mechanical analysis to simulate. The large displacement theory is used to conduct mechanical analysis. The effect of constraints on distortion and residual stresses are numerically studied. The predicted stresses and distortion results of different cases are discussed and presented.

The raceway plays an important role in the mass and heat transportation inside a melter gasifier. Considering that pure oxygen at room temperature instead of hot air is injected into the melter gasifier, a two-dimensional mathematical model at steady state is developed in the current work to describe the effect of the additional gas injection on the characteristics around the raceway in melter gasifier. The results show that a high-speed jet with a highest temperature above 3500 K could be found in front of tuyere. Furthermore, a small scale of gas flow circulation occurs in front of tuyere that results in a more serious thermal damage to tuyere. In order to decrease the gas temperature in the raceway to prevent the blowing-down caused by tuyere damage, the additional gas, including N 2 , natural gas (NG) and coke oven gas (COG) should be injected through the tuyere. Compared with N 2 , additional fuel gas injection gives full play to the high temperature reduction advantage of hydrogen. In addition, considering the insufficient hearth heat after injecting NG and the effective utilization of secondary resource, an appropriate amount of COG is recommended to be injected for optimizing blast system.

Temperature significantly affects the physical and mechanical properties of granite. To have a comprehensive understanding of the thermal cycle effect on uniaxial compressive strength ( UCS ) and thermal damage rate, a series of thermal cycle experiments on granite specimens were carried out with five types of designed temperatures and five types of cycle number of thermal treatments. The experimental results indicate that UCS decreases and thermal damage rate increases as temperature and thermal cycle increase. UCS of specimens cooled in water condition after thermal damage treatment are lower than those cooled in air condition. In addition, two new phenomena related to thermal damage rate were observed. Firstly, previous studies have shown that a rapid value reduction of UCS of specimens with one thermal cycle treatment under air cooling condition can be observed at 400 ∘ C. While the temperature threshold for the specimens treated with more than one thermal cycle under water cooling condition increases to 550 ∘ C. Secondly, a thoroughly antipodal evolution law of the thermal damage rate for the specimens with multiple thermal cycle treatments is also observed as compared to those treated by only one thermal cycle. These differences might be induced by the different microcrack initial time and their development speed. The new findings are important to understand the failure mechanism and variation process of physical and mechanical properties of granite specimens subjected to thermal cycles.

Improving the cementitious activity and volume stability of steel slag by thermal reconstruction is an innovative method for efficient utilization of steel slag. In this study, different amounts of CaF 2 and CaSO 4 were added to steel slag as a mineralizer based on the determining admixtures needed for the reconstruction reaction, and the effects of CaF 2 and CaSO 4 on the cementitious activity and volume stability of the reconstructed steel slag were investigated. The results show that when the CaF 2 content is increased to 5 wt%, the cementitious activity index of the reconstructed steel slag gradually increases to 92%, which is 12% higher than the first level technical requirement specified by the national standards, and the free CaO ( f - CaO) and MgO ( f -MgO) contents gradually decrease to 0.35 and 0.13 wt%, respectively. With increasing CaSO 4 content, the cementitious activity index first increases and then decreases, while the contents of f -CaO and f -MgO show the opposite trend. When the CaSO 4 content is 2 wt%, the activity index is 105%,which is 25%higher than the first level technical requirement specified by the national standards, and the f -CaO and f -MgO contents reach minima of 0.44 and 0.35 wt%, respectively.

The comprehensive utilization of stainless steel slag is one of major problems to be solved at “green steelworks”. Precipitation of spinel crystals can effectively detoxify residue. The effect of basicity defined by ω (CaO)/ ω (SiO 2 ) ratio on precipitation of spinel crystals in a CaO-SiO 2 -MgO-Cr 2 O 3 -8 wt % FeO system has been determined with such tools as FactSage 7.1, SEM-EDS, IPP 6.0 and XRD. The FactSage 7.1 results showed that the rate of spinel phase enrichment with chromium was about 98% for the system basicity less than 1.4 and about 78% above this value. The precipitation of solid particles in solution appeared to be significantly influenced by basicity. With its increase the solid phase grew, the liquid one reduced, the particle diffusion was limited, and the growth of spinel crystals was inhibited. The spinel crystal size increased rapidly with decrease of basicity. When basicity increased from 0.6 up to 1.0, the crystal size decreased sharply from 12.30 μm down to 6.22 μm, and the reduction constituted as much as 49.43%. When basicity increased from 1.0 up to 2.2, the spinel crystal size moderately decreased from 6.22 μm down to 4.47 μm. Therefore, reduction of basicity is conducive to spinel crystal enrichment with chromium what appears to be a key factor to control basicity at detoxification of the chromium-containing steel slag.

In order to improve the surface defects of strand, the mold flux is exploited for the Ti-bearing welding wire steel ER80-G. The composition of mold flux is designed by analyzing the solidification characteristics of ER80-G and the slag system isothermal section diagram, simulating by the FactSage thermodynamics software. The Ti-bearing welding wire steel ER80-G belongs to the peritectic steel. The melting point range of the newly designed mold flux system is from 1030 ∘ C to 1129 ∘ C, the melting rate range is from 58 s to 64 s, the viscosity range at the temperature of 1300 ∘ C is from 0.33 Pa·s to 0.50 Pa·s, the crystallization temperature range is from 1160 ∘ C to 1293 ∘ C, the crystalline fraction range is from 34% to 85%. The surface defects of strand which transverse depression, longitudinal depression, slag runner and so on were obviously improved when the newly design mold flux F3, F5, F9 were used to the production respectively. Those results suggest that 0.9 basicity with 28.4%-CaO, 31.6%-SiO 2 ,3%-MgO, 10%-Na 2 O, 10%-CaF 2 , 6%-Al 2 O 3 , 1%-Fe 2 O 3 , 10%-T c and all groups with 1.0 and 1.1 basicity show the best properties for Ti-bearing welding wire steel ER80-G.

Blast furnace heat is the key to the blast furnace’s high efficiency and stable operation, and it is difficult to maintain a suitable temperature for large blast furnace operations. When designing the furnace heat prediction and control model, parameters with good reliability and measurability should be chosen to avoid using less accurate parameters and to ensure the accuracy and practicability of the model. This paper presents an effective model for large blast furnace temperature prediction and control. Using thermal equilibrium and the carbon-oxygen balance of the blast furnace’s high-temperature zone, the slag-iron heat index was calculated. Using the relation between the molten iron temperature and slag-iron heat index, the furnace heat parameter can be calculated while production conditions are changed,which can guide furnace heat control.

In this study, the effect of solid solution temperature on microstructure and mechanical properties of the AA7075 alloy after T6 heat treatment was investigated. Following solid solution at five different temperatures for 2 hours, the AA7075 alloy was quenched and then artificially aged at 120 ∘ C for 24 hours. Hardness measurements, microstructure examinations (SEM+EDS, XRD) and tensile tests were carried out for the alloys. The results showed that the increased solid solution temperature led to formation of precipitates in the microstructures and thus caused higher hardness and tensile strength.

The viscosity and break temperature of La 2 O 3 –SiO 2 -FeO slag was investigated to develop low-Al 2 O 3 or Al 2 O 3 -free slag for the effective recovery of rare-earth metals. When La 2 O 3 content is fixed (45, 50 and 55 mass%), the viscosity and break temperature of La 2 O 3 –SiO 2 -FeO slag decrease with an increase in FeO content and a decrease in SiO 2 content. A higher La 2 O 3 content in the La 2 O 3 -SiO 2 -FeO ternary slag yields a lower slag viscosity but a higher break temperature. Individual minor components of Al 2 O 3 , MnO and B 2 O 3 does not affect, or decreases slightly the viscosity of La 2 O 3 –SiO 2 -FeO slag, whereas the slag break temperature is reduced so that the reduction ability order is ranked as B 2 O 3 > Al 2 O 3 > MnO. A small amount of two components Al 2 O 3 + MnO and Al 2 O 3 + B 2 O 3 has little effect on the viscosity of the slag but it has an additive effect on the slag break-temperature reduction.

Tensile deformation and fracture behaviour of AISI 431 martensitic stainless steel, over the temperature range of 300-823 K, has been examined. Yield and ultimate tensile strength values decreased gradually from room temperature to intermediate temperatures, followed by a rapid decrease at high temperatures. At the intermediate temperatures (523-673 K), the steel exhibited jerky/serrated flow and anomalous variations in terms of a plateau in flow stress/strength and work hardening parameters and minima in ductility. These manifestations were identified to be the signatures of dynamic strain ageing, operating at these temperatures. At high temperatures, a rapid decrease in flow stress/strength values and increase in ductility with increasing temperature indicated the dominance of dynamic recovery. The fracture remained transgranular ductile at all temperatures. Work hardening relations that best described the flow behaviour of AISI 431 steel were identified. Variations of the work hardening parameters with temperature were consistent with the variations exhibited by strength and ductility values.

Metal matrix composites are an essential product used in engineering materials. This product has wide applications in automotive, aerospace, and other uses because of their lower density, good specific strength, best machinability, and better mechanical properties compared to Al 6063 alloy. In this paper, four different reinforced such as (MA), (MCA), (NFC) and (SA) with a constant rate of 5 wt.% for each reinforced element used and mixed with Al 6063 alloy as a metal matrix composite by using modified two-step mechanical stirrer and having three blades at each step. Coated carbide tool insert was carrying out the turning process. Surface roughness measured after turning of every change in cutting speed. Average chip length and its shape style formation performed within cutting speeds of 10 and 90 m/min, which appears in different length and shapes. Mechanical properties, damping characteristics, and wear loss improved dramatically by adding all reinforced composites to the base Al 6063 alloys. As the results of experiments, the surface roughness decreased by adding all four types of reinforcements. The mechanical properties, wear loss and damping characteristics improved by the constituents of all kinds of reinforcements and also by mixing of all types of constituents together. The effects of MA and NFC are more compared to MCA and SA for improving all conditions of experimental results. Microstructure observation produces compact grain boundaries with strong grains of metal matrix composites compared to Al 6063 alloys.