Volume 13, Issue 1-2

Rubber of different varieties is effectively used in various engineering as well as other applications. As an engineering material it is very useful and suitable for different engineering advantages. Though its use is not new in that sense but in the recent time the use of rubber is gaining popularity due to several property enhancements as a result of varied advanced researches and new developments in this area. Simultaneously with these newer developments, the need of the hour is to find out the behavior pattern of such developments. Amongst various rubber EPDM emerges as a dominant elastomer for major applications in automobiles, construction works, electric and electronic industries due to their outstanding heat, ozone and weather resistance ability along with the resistance to polar substances and steam. In automobiles EPDM has a common use as seals, which includes but not limited to, door seals, window seals, trunk seals and hood seals etc. Frequently these seals are becoming the source of noise due to friction and wear. Thus, proper contact iteration is required to provide optimum and satisfactory performance of those parts. In the present work compression tests have been carried out to realize the flow characteristics of EPDM rubber of different hardness. Cylindrical specimens have been compressed in between two flat mild steel platens of INSTRON in lubricated conditions. Water, talc and grease have been used as lubricants. Flow characteristics like load-vs-elongation, true stress-vs.-true strain, specific energy, hysteresis and loss factors have been estimated from the experimental data. Test results revealed that the compressive flow behavior of EPDM is highly dependent on the hardness and different conditions of lubrication. However, as the properties of any viscoelastic material are very difficult to be predicted, hence more researches and experimentations are needed to arrive at the final conclusion.

Friction stir welding is a novel welding technology, which has been applied widely in aerospace, traffic, marine industries because of its unique mechanical properties, metallurgic structure and environmental friendly. In the present study, the effect of pin rotational speed and traverse speed at constant downward force on microstructure and mechanical properties (Tensile and Hardness) of wrought aluminum alloys AA6351-T6 and AA2024-T6 of dissimilar friction stir welds were studied. Transverse tensile strength and hardness profiles on either side of the weld centre line were evaluated and the results were compared with base materials at room temperature.

Austenitic stainless steel sheets have gathered wide acceptance in the fabrication of components, which require high temperature resistance and corrosion resistance, such as metal bellows used in expansion joints in aircraft, aerospace and petroleum industry. In case of single pass welding of thinner sections of this alloy, Pulsed Current Micro Plasma Arc Welding (PCMPAW) was found beneficial due to its advantages over the conventional continuous current process. This paper highlights the development of empirical mathematical equations using multiple regression analysis, correlating various process parameters to pitting corrosion rates in PCMPAW of AISI 304L sheets in 3.5 Normal NaCl. The experiments were conducted based on a five factor, five level central composite rotatable design matrix. The adequacy of the model is checked by Analysis of Variance (ANOVA). The main effects and interactions effects of the welding process parameters on pitting corrosion rates of the welded joints are studied using surface and contour plots.

The sharp freshly ground tool forms wear land with machining. The present work attempts to measure the non-zero inclination of flank wear land with respect to cutting direction and study the effect of the machining parameters, like speed, feed, rake angle and clearance angle, on the formation of non-zero flank wear land inclination. The experimental plan was based on the face centred, central composite design (CCD). The results clearly indicated the presence of non-zero flank wear land inclination with the direction of cutting. The interactions between machining parameter strongly influences flank wear land inclination. This information may be helpful in improving existing machining model or to develop a new model.

Electrochemical machining (ECM) is increasing its importance in machining of metal matrix composites (MMC) due to some specific advantages which can be exploited during machining operation. In ECM the quality of the surface produced is also depends on the workpiece physical and electrical properties along with the process parameters like voltage, feed rate, electrolyte concentration, type of electrolyte, current, gap between electrodes etc. Therefore, in the present work the percentage of reinforcement of the particulates in the matrix is considered one of the process parameters along with the applied voltage, electrode feed rate and electrolyte concentration. A mathematical prediction model of the radial over cut (ROC) was developed using response surface methodology (RSM). The effects of electrochemical machining parameters on the Radial over cut were evaluated. The contour plots were drawn to study the effect of various process parameters and their interaction. In this work the predicted values and measured values are quite close to each other. Therefore, the developed model can be effectively used to predict the radial over cut on electrochemical machining of Al-B 4 C composites.

Recently, reduction of the steelmaking slag stock in Japan has been required, but utilization of steelmaking slag is restricted due to its chemical properties. On the other hand, the price of phosphorus ore is increasing rapidly due to the very tight supply/demand balance worldwide. In this work, (Fe t O) and (P 2 O 5 ) reduction in steelmaking slag and recovery as a phosphorus source were investigated in feasibility studies and laboratory-scale experiments in order to develop a rational recycling process for steelmaking slag. The results are summarized as follows: (a) Steelmaking slag was reduced by carbon under high temperature conditions (1373–1873 K), and high-P hot metal was recovered. The phosphorus content of the reduced slag was <0.3 mass%. (b) Higher temperatures were required for slag reduction with carbon, corresponding to increasing slag basicity. (c) The oxygen partial pressure calculated from the FeO content ranged from 10 −13 to 10 −17  atm. More than 50 mass% of phosphorus in the slag can be removed under the condition that FeO activity is less than 0.01. (d) From the mass balance of phosphorus, 0–30 mass% of undefined phosphorus was observed, which was estimated by thermodynamic calculations and SEM-EPMA analysis to be caused by gaseous dephosphorization. (e) The gaseous dephosphorization ratio becomes more than 10% at the condition of log  L P  ≤  0. (f) Phosphorus was enriched in slag to higher than 30 mass% P 2 O 5 by dephosphorization of high-P (1.05 mass%) hot metal.

KTH Steel Scrap Model calculates material flows of iron and steel in the Swedish society based on statistics, mass balance and mass flow analysis and industry knowledge. The material flows of iron and steel were calculated for external scrap consumption, internal scrap, domestic steel scrap arising and net flow of iron and steel into the Swedish society. Model output on external steel scrap consumption and domestic steel scrap arising was compared to an earlier analysis done by Jernkontoret for the timeline 1980–2009. The results show that mass balance calculations are area wise corresponding to consumption figures based on trade statistics. In addition the difference in trend is assumed to be mainly due to stocking effect. Furthermore it is shown that mass balance and mass flow models could be used as a tool to calculate apparent scrap consumption based on crude steel production figures by process type.

Titanium-silicon alloys have been electrochemically extracted from the multi-component titanium-bearing compounds in molten calcium chloride electrolyte. Sintered pressed pellets of titanium-bearing compounds served as the cathode, and the electrochemical experiments were carried out systematically at 900 °C, 3.1 V and 1000 °C, 3.8 V using a graphite-based anode and an improved solid oxide oxygen-ion-conducting membrane (SOM)-based anode, respectively. The mineral composition and morphology of the obtained products were examined. The current features and the reaction mechanisms of the electrochemical reduction process are discussed. Comparisons between the graphite- and SOM-based anode systems are also carried out, and the results show that the improved SOM-based anode electrolysis system exhibits higher current efficiency and reduction rate than the graphite-based anode electrolysis system. Electrolysis of about 1.5 g titanium compounds using the SOM-based anode system can be finished within 6 h, and the current efficiency reaches approximately 50%.

The effects of chemical compositions and austenitizing temperature on the formation of intragranular acicular ferrite (IAF) of 16Mn steel, a grade of low alloying steel with carbon content of 0.13∼0.19% and manganese content of 1.20∼1.60%, were systematically investigated. The in situ observation of the evolution of IAF at Mg-containing inclusions was carried out using a high-temperature laser scanning confocal microscopy (LSCM). The nucleation and growth of ferrites, the formation of IAF induced by inclusions, and the size of austenite grain at 1200 °C was directly observed using the LSCM. The results show that the inclusions can be transformed into MgAl 2 O 4 , Mg 2 SiO 4 and MgO after treated by Mg. Trace amount of Mg can induce the IAF nucleation. With the increasing of Mg addition, the percentage of IAF in steel greatly increases, while the optimum content of Mg is around 0.0022 wt%. The appropriate austenitizing temperature is around 1200 °C and the optimal prior austenite grain size is about 130 µm. The temperature range for IAF transformation is around between 571 °C and 627 °C, and the time for which is about 12 s. The disregistries between MgAl 2 O 4 , MgO and α-Fe are as small as 0.6% and 4.03%, they are so small that may act as highly effective nuclei of IAF during γ → α transformation.

It is an effective way to decrease power consumption, pollution emission, to increase productivity and improve ingot quality by using lower CaF 2 content even CaF 2 free slag during the electro-slag remelting (ESR) process. In this study, a conventional slag, namely ANF-8 with composition of 60 mass%CaF 2 -20 mass%CaO-20 mass%Al 2 O 3 was chosen as a reference slag. A new quaternary slag system of CaF 2 -CaO-Al 2 O 3 -SiO 2 with four lower CaF 2 content levels in mass fraction, 59%, 55%, 50%, 45% were prepared and labeled as S 1 , S 2 , S 3 and S 4 respectively. The effects of CaF 2 content and temperature on the physical properties of the slag were investigated. The results showed that the melting points and the conductivity of the samples S 1 –S 4 were all lower than those of the sample ANF-8. The melting point and the conductivity (1600 °C) of Sample S 4 achieved 1372 °C and 1.936 Ω −1 ·cm −1 , respectively. The conductivities of Sample S 4 at 1550–1650 °C reached 1.741–2.131 Ω −1 ·cm −1 , and were lower than those of ANF-8 and S 1 –S 3 . Considering the physical properties of the four new slags in the CaF 2 -CaO-Al 2 O 3 -SiO 2 quaternary system and low CaF 2 in the slag to decrease the power consumption and pollution emission, the slag S 4 was the most suitable for the ESR process.

Copper smelting in one processing step directly from concentrates to blister copper has been realized on an industrial scale in a few smelters, using concentrates with a high Cu/Fe-ratio. The fluxing of any direct-to-blister slag is demanding task as it must be fluid and maintain suitable properties in the oxidising conditions of copper making, and the reducing conditions of slag cleaning. The smelting slags in the direct-to-blister furnaces contain much more chemically dissolved copper than typical matte making slags. In this investigation, an industrial direct-to-blister slag was used in a freeze lining growth kinetics study. The freeze lining was formed on a water cooled metal finger at typical smelting temperatures using different dipping times from 5 to 120 min. The growth kinetics of the lining was very fast in the initial stage of the slag contact with the cooled metal surface. The quenched samples showed characteristic solidification zones from the cold end towards the hot side of the freeze lining and the molten slag shown already in other freeze linings and different slag types. The slag chemistry modifies the solidification pattern very much and thus the crystalline phases in the lining included also phases created by the high copper oxide concentration as well as the specific gangue assay of the smelters feed mixture. The thermal stability of the freeze lining in high-in-copper DB slags is discussed as well as the mechanism of delafossite precipitation.

The dross formation is closely related with the solubility of Fe in the molten bath. When the Fe level exceeds the saturation solubility of liquid, the dross precipitates in the form of intermetallic compounds. Inductively coupled plasma atomic emission spectrometry (ICP) was used to determine the content of Fe in molten bath. The morphology of the bottom dross was observed by scanning electron microscopy (SEM). Based on the experimental results and the calculated phase diagram of the Al-Zn-Si-Fe system, the effects of bath temperature and Si content in the molten bath on the Fe solubility were analyzed, and then the mechanism of dross formation was investigated. The results showed that when the bath temperature decreased from 630 °C to 590 °C, the solubility of Fe in liquid reduced from 0.12 wt.% to 0.06 wt.% and 0.17 wt.% FeAl 3 would precipitate from the liquid. Compared with the Fe dissolution lines at different Si content, it can be seen that the solubility of Fe in Al-Zn melt increased with the increasing of Si content from 0.5 wt.% to 1.5 wt.%. However, the amount of precipitated FeAl 3 in 55wt.%Al-Zn-1.5Si molten alloy (0.17 wt.%) was greater than that in 55wt.%Al-Zn-0.5Si molten alloy (0.14 wt.%) in the same temperature range. It means that the more the Si contents in the liquid, the greater the amount of dross formation.

With the Single Hot Thermocouple Technique the solidification behaviour of metallurgical slags has been studied, building TTT and CCT diagrams, with in situ observation for melting and solidification under various thermal conditions. Slags in the system CSTNA were studied, analysing the kinetics of crystals growth. Following findings are reported: (i) for the slag CS (%CaO/%SiO 2  = 0.7) no crystal is observed during continuous cooling even to low cooling rates, but on the other hand intense crystallisation is obtained when increasing the temperature after reaching a particular range of lower temperatures; (ii) it was observed that the longer the duration of the superheating is, the longer the incubation times for a slag CST (41 %CaO, 29 %SiO 2 , 30 %TiO 2 ) becomes; (iii) the addition of Na 2 O into the CST slag system shortens intensely the crystals incubation times at TTT diagrams to the range of seconds.

Slag film samples together with their associated mold fluxes were collected after service during tail out at the voestalpine Stahl GmbH continuous casting machine. The slag films were obtained after casting steel grades different in Al or Ti content and mineralogically investigated. Three distinctive layers could be determined within the slag films. A so called glassy layer, a crystalline layer and a layer, which has been liquid during casting and solidified afterwars, could be observed. Cuspidine (Ca 4 Si 2 O 7 F 2 ) is the prevailing crystal phase in the crystalline layer. Casting alloyed steel grades the structure of the crystalline layer will be modified. With increasing Al 2 O 3 content of the slag, due to interactions with the steel, nepheline ((Na,K)AlSiO 4 ) was formed besides cuspidine. Here the distinctive needle like shaped cuspidine is remarkable. With casting steel grades with even more elevated Al content, the slag composition shows a strong decrease of silica and an increase of alumina. Therefore no longer cuspidine but fluorite (CaF 2 ) and a so far unknown phase rich in alumina are the main crystal phases. When casting steel grades with increased Ti content, perovskite (CaTiO 3 ) will be formed additionally to cuspidine in the crystalline layer. In addition quench tests of the original mold powders as well as DTA and viscosity measurements of the original mold powder and the slag films were performed. The methods revealed the impact of the Al 2 O 3 and TiO 2 pick-up on the crystallization temperature, the phase composition and the viscosity.

Reliable values of thermal conductivity of molten silicates are strongly requested to establish a model which can describe the relationship between thermal conductivity and structure of the molten silicates. Thermal conductivity of R-Na 2 O-SiO 2 (R = Al 2 O 3 , CaO) molten slags has been measured by using the novel laser flash method. A thin platinum crucible was filled with silicate melt and the bottom surface of the platinum crucible at high temperature was irradiated by a pulsed laser. After irradiation, a temperature decay of the bottom surface of the platinum crucible was measured with an InSb infrared detector. The value of the thermal conductivity was determined by fitting the measured temperature response curve to theoretical one with a least square method. Measured thermal conductivity slightly depends on temperature in molten state with the chemical compositions of the slags presently investigated. On the other hand, the thermal conductivity was found to decrease with increasing NBO/T (Non-Bridging Oxygen ions / Tetrahedrally coordinated cation) values.

For integrated steel plants, hot metal with silicon content larger than 1.0% cannot be used in BOF (Basic Oxygen Furnace) process unless mixed with low silicon-content hot metal. Slopping is the major disadvantage of BOF operation with high silicon-content hot metal during blowing. But for steel plants with newborn single blast furnace, such as Dragon Steel Corporation, the way of mixing hot metal cannot be delivered in exception of dumping. In order to decrease the amount of hot metal dumping, China Steel Corporation successfully developed a new BOF process for blowing hot metal with silicon content higher than 1%, with a maximum value reaching 2%. Through persistent tests in 250-ton BOF by studying slag properties and blowing models, a double-slag method was developed to blow high silicon content hot metal. During blowing test of high silicon hot metal for three heats, desiliconization slag was sampled during deslagging. The slag composition and mineral phase were examined by the usual XRF chemical analysis, as well as SEM and XRD studies to provide an important reference in the slagging practice for double slag operation.

The electrolytic method for directly extracting metals from the cathode of their its oxide has been called as “electro-deoxidation”. TiO 2 cathode in molten CaCl 2 has been developed more than 10 years. Two different mechanisms (“FFC Cambridge” and “OS”) were proposed to describe this electrochemical process. In order to further explore the mechanism, a dense cathode was designed in the present study, and an electrical conductor (Mo bar) was connected with the cathode, but without direct connection with molten salt to get rid of the possible electrochemical reaction between electrical conductor and melt. The cathode after the electrolytic experiment was examined by using SEM technique. The SEM observation of the cathode showed a layer-structure with dense core and porous product in outer layer(s). The electrical resistance of the core was found much lower than that of the original cathode. The result of electro-deoxidation experiments by present authors indicated that the “FFC-Cambridge” mechanism may give a better explanation for the electro-deoxidation process of dense cathode at the initial time.

Laboratory experiments exploring the interaction between molten steel, slag and lining refractory were performed. The transient erosion and reaction over time were investigated, and the transient change of the reaction layer and inclusions generated in the molten steel were evaluated using optical microscopy and SEM-EDS. Without slag addition before remelting, the FeO from reoxidation entered the space between the lining refractory and the steel and strengthened the erosion of the lining refractory. Several layers were found from the steel to the original lining refractory layer: steel phase, FeO layer, a FeO-rich lining layer and an Original Lining (OL)-rich lining layer. The thickness of the reaction layer increased nearly linearly with the reaction time at an erosion rate of 4.2 µm/min. With slag addition before remelting, the reaction layer between the steel and the original lining materials included several sub-layers: a gap, a slag layer, an FeO-rich lining layer and an Original Lining (OL)-rich lining layer. The thickness of the reaction layer nearly linearly increased with the reaction time and with an erosion rate of 5.7 µm/min. Slags were entrained into the steel occasionally.