Volume 65, Issue 4

AISI 304 stainless steel specimens are deposited with Ti using physical vapor deposition method for 3, 5, and 8 min. Then, specimens are subjected to wear test with 10 and 20 N applied loads in seawater and boric acid reinforced seawater. Optical microscope and scanning electron investigations showed that ultrashort PVD process formed non-uniform Ti deposit zones on the substrate. Abrasive wear mechanism is observed for 10 N applied load and increasing the applied load to 20 N transformed the wear into adhesive which is attributed to counteract dynamic reaction of the surface. Besides, boric acid addition to seawater lowered the wear rate and coefficient of friction for all tests and stick-slip phenomenon is removed in boric acid addition. In corrosion properties, boric acid addition improved the corrosion resistance of the specimens.

The welding parameters optimization of TC4 titanium alloys/304 stainless steel (TC4/304 SS) by friction stir lap welding (FSLW) based on orthogonal test was researched. The results show that when the rotating speed was constant, the area of the high temperature zone and the peak temperature decreased with the increase of the traversing speed; when the traversing speed was constant, the area of the high temperature zone and the peak temperature increased with the increasing rotating speed. Among them, under the condition of low heat input, the interface temperature was about 912 °C, the material at the interface cannot fully react, and there was no formation of a large amount of brittle and hard intermetallic compounds; under the condition of medium heat input, the interface temperature was about 930 °C, this temperature caused a large amount of brittle and hard intermetallic compounds at the interface; under high heat input, the interface temperature was about 975 °C, a large number of intermetallic compounds were not formed at the interface.

In this study, the effect of the buttering layer (18.5% Cr + 9% Ni) and the chemical composition of the hardfacing filler materials on the microstructure and wear behavior of the structural steel (S355JR) was investigated. The chromium-based hardfacing alloys deposited by shielded metal arc welding (SMAW) have also been investigated to establish the relationship between microstructures and wear properties. The microstructure of hardfacing deposits has been examined by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. A linear reciprocating abrasive wear test experiment was conducted on the hardfacing deposits using an Al 2 O 3 ball under constant wear test conditions. The experimental results show that the microstructure of hardfacing deposits consists of martensitic matrix and complex (M 7 C 3 ) carbides. In addition, the increased chromium concentration of filler materials leads to an increase in the volume fraction of the primary carbides in the matrix of hardfacing deposits. The buttering layer caused the formation of diluted hardfacing deposits. Also, it significantly reduced the hardness and wear rate of hardfacing deposits. Fe14-Fe14 hardfacing deposit has exhibited the best wear properties with a low coefficient of friction.

In this paper, different hexagonal lattice structures of the tensile test specimens were designed, manufactured by additive manufacturing, and tested in three different lengths. Moreover, flat shape tensile test specimens were designed without lattice structure. Mechanical behaviors were obtained using a tensile testing machine and analyzed at a finite element program. Effect of lattice shape and infill density on mechanical behavior was investigated. Results were compared with finite element analysis to validate the simulation. Main objective of this paper is to investigate the tensile test properties of polylactic acid (PLA) test specimens with different hexagonal-shaped lattice structures and verify their finite element model. It is concluded that increasing hexagonal lattice size increases ductility up to certain degree. Elastic modulus of 15% and 100% infill density specimens was nearly same at lattice region.

The heat treatment of SA508-3 steel was carried out by means of quenching and manual aging. The microstructure and mechanical properties of the prepared SA508-3 steel were analyzed and tested. The results show that the main composition of the matrix of SA508-3 steel is bainite, and the main composition of the second phase is alloy cementite containing Fe, Mn and C. The second phase is distributed at both the matrix and grain boundaries. The second phase can prevent the dislocation from moving by fixing the dislocation, and the second phase at the grain boundary can strengthen the matrix by hindering the grain boundary movement. The stress-strain curves of SA508-3 steel under different loading rates show that when the strain rate is greater than 0.5 m s −1 , the fracture mode of the steel is brittle fracture, and when the strain rate is less than 0.5 m s −1 , the fracture mode of the steel is ductile-brittle bonding fracture. The second phase of the crack first diffuses to the grain boundary, reducing the strength of the grain boundary. When the loading rate is high, the second phase at the grain boundary cannot diffuse in time, and the material undergoes transgranular fracture and intergranular fracture.

To realize high-throughput tensile testing of miniaturized specimens, the size effect was investigated. High-throughput tensile testing was used to characterize the mechanical properties of steel in the micro-zone. Miniaturized specimens with diameters ranging from 0.7 mm to 2.5 mm were cut from low-alloyed steel and tested, and the deviations between the results of miniaturized and conventional sized specimens were examined. The results showed that the size effect was negligibly small for the tensile strength. However, the upper yield strength, lower yield strength, and plastic extension strength of miniaturized specimens decreased as the specimen diameter decreased. It was found that a diameter of 1.5 mm was critical for the tensile testing of miniaturized specimens. As the specimen diameter decreased toward 1.5 mm, the strength parameters gradually decreased, and as the specimen diameter further decreased from 1.5 mm, the strength parameters increased. In contrast, as the specimen diameter decreased from 1.3 mm, the elongation after fracture decreased. However, the percentage reduction of area did not vary between miniaturized and conventional sized specimens.

The microstructure effect is critical in the near-threshold region in terms of fatigue crack propagation. Despite numerous studies on the crack growth phenomenon in the literature, there is still no comprehensive understanding of the mechanism behind it. The fatigue crack growth mechanism occurs in the plastic zone region, which is quite small in size; the order is regarded as microstructural units, particularly at low stress intensities. Microstructural differences caused by heat treatment methods are frequently attributed to changes in monotonic and yield strength, resulting in differences in plastic zone size. The driving force required for crack growth under alternating loading is proportional to the plastic zone size ahead of the crack tip. When the microstructure is modified using isothermal transformations, the stress intensity near the threshold and corresponding crack propagation rates were found to be affected by stress ratio, material yield strength, particle size distribution, and impurity segregation. The crack growth threshold Δ K 0 is discovered to be inversely related to steel strength, and a relationship between Δ K 0 and cyclic yield stress is established. In the scope of this paper, annealed and tempered conditions were investigated to assess near threshold behavior for AISI 4340 steel. Effect of microstructure will be detailed around low stress intensities via performed crack growth tests.

Biomaterials research has gained considerable momentum recently. The development of technology and the changing human lifestyles have also changed human health needs. The developed materials for use in different areas like in medical products and living bodies have necessitated adding biocompatibility to the mechanical, physical, and chemical properties of these materials. This article is a review of the concept and evaluation of biocompatibility. It explains how biomaterials change with the development of technology, human changing lifestyles, and needs, and how these materials are developed with the same technology. It contains what biocompatibility is, the factors that affect biocompatibility, what can happen in case of low biocompatibility, and the standards and work plans required for tests such as hemocompatibility, genotoxicity, toxicokinetic, and immunotoxicology for biocompatibility..

Aluminium matrix composites with high abrasion resistance, which can adapt to high temperatures and difficult operating conditions, are needed in the automotive and aerospace industries. For this purpose, Al–12Si–TiB 2 –Al 2 O 3 composites were developed with the addition of TiB 2 –Al 2 O 3 ceramic reinforcements at different rates and Gr at a constant rate. High densities were achieved by using the hot pressing method with powder metallurgy. Microstructural analyzes (SEM, EDS, X-RD) of the produced samples were made. In addition, mechanical properties (hardness and three-point bending) were investigated. The best tribological features were determined with the help of Taguchi, ANOVA and the prediction model. As a result, with the addition of TiB 2 and Al 2 O 3 reinforcements to the Al–12Si matrix, significant increases in hardness occur. In the bending analysis, it was determined that the reinforcements made the hybrid composite strong up to a certain point. From a tribological point of view, the A3 hybrid composite showed the best wear performance. Test conditions were analyzed with the help of Taguchi L 18 orthogonal array and analysis of variance (ANOVA). With the help of ANOVA, it was determined that the most effective factors on the response parameters were the applied load and MMC type.

The Sverker 3 steel was treated by solid boriding in the range 1173–1273 K for holding times ranged from 1 to 7 h. The processes resulted in two-phase (FeB + Fe 2 B) boride layers except the treatment at 1173 K for 1 h where the Fe 2 B was formed only. The growth of borides obeys a typical parabolic law, with the maximum thickness of 120 ± 4.5 µm. Considerable redistribution of carbon and alloying elements took place during boronizing; carbon and silicon were pushed out from borides while chromium and tungsten were rather gathered in these compounds. The microhardness of Fe 2 B ranged between 1600 and 1700 HV 0.1, and that of FeB reached 2100–2200 HV 0.1. The average diffusion coefficient (ADC) approach was applied by assuming the linearity of boron concentration profiles across the iron boride layers. This approach allowed us to obtain the boron diffusivities in both the FeB and Fe 2 B. Afterwards, the boron activation energies in both layers were obtained by fitting the temperature evolution of calculated boron diffusivities in the two iron boride phases with the Arrhenius relations. The assessed boron activation energies in FeB and Fe 2 B were, respectively, 215.18 and 203.6 kJ mol −1 . Finally, a comparison of these values of energies was made with literature results.

Accumulation of industrial waste is a serious environmental problem, which lead to air and water pollution. Addition of industrial waste in polymer composites as reinforcement can enhance the various properties. To overcome this issue, an attempt has been made to investigate mechanical, tribological and water absorption behaviour of industrial waste (red mud) based sisal/glass fiber reinforced hybrid composites and also no research has been done on this. In this work, prepared the composite specimens using sisal fiber (35, 30, 25 and 20 wt%), red mud (0, 5, 10 and 15 wt%) through hand layup technique. In addition to this, glass fiber (5 wt%) and polyester matrix (60 wt%) are kept as constant. From the results, it is observed that, enhanced mechanical properties, minimum wear behaviour and good water resistance were observed on 30 wt% of sisal fiber and 5 wt% of red mud filled composite and recommending this material for marine applications due to good water resistance in sea water. Morphological analysis shows fiber breakages, voids, wear debris, minor cracks, voids and delamination.

In this study, two different aluminum alloy (AA1030/AA7075) pairs were joined using friction stir welding (FSW) method. Tool rotation speed, welding speed, and stirrer geometry were chosen as variable welding parameters. The welded joint zones were evaluated for both microstructural and mechanical properties such as ultimate tensile strength (UTS) and nugget hardness (H). Optimum welding parameters were determined using multi-criteria decision making techniques such as rank preference technique by similarity to ideal solution (TOPSIS) and gray relational analysis (GRA). At the same time, the performances of the TOPSIS and GRA methods were compared.

In this study, the effect of modification Al-12Si (Etial 140) casting alloy with Al10Sr, CuSn5, and Al10Sr + CuSn5 master alloys has been investigated with respect to the cutting forces. In order to characterize the morphology of materials used in this study, metallography, hardness, density tests, and chemical analysis were performed. An optical microscope was used to examine the microstructure of the samples. Machinability tests were performed with the turning method by using a titanium diboride-coated cementite carbide cutting tool. All experiments were carried out under dry machining conditions with three different cutting speeds and feed rates with a constant cut depth. After the turning test, scanning electron microscope (SEM) images were used to examine the build-up edge (BUE) formation on the cutting tool. It was determined that the modification process has a positive effect on increasing the density and hardness. According to the results, it was observed that cutting ( Fc ), feed ( Ff ), and tangential ( Fr ) forces decreased for all material groups with increasing cutting speed V. Furthermore, Fc , Ff , and Fr forces increased for all material groups with increasing feed rate f . Finally, the highest cutting forces were observed on the Etial 140 c + Al10Sr master alloy.

The main objective of this investigation is to analyze the influence of DCT cycles on microstructural evolution, surface roughness, hardness and dimensional stability of AISI D2 tool steel for cutting tools and dies applications. The cryogenic quenching was done using gaseous nitrogen. The AISI D2 tool steel was subjected to two DCT cycle: DCT-I (Hardening + DCT + tempering) and DCT-II (Hardening + tempering + DCT). The dimensional stability of AISI D2 tool steel was evaluated using standard Navy C-ring test. The coordinate measuring machine (CMM) was employed for the precise measurement of Navy C-ring subjected to different DCT cycle. The surface roughness was evaluated with R a (arithmetic mean roughness) and R t (total height of roughness profile) values using surface roughness tester. The microstructural features were analyzed using optical (OM) and scanning electron microscopy (SEM). The electrical resistivity and hardness of treated samples were measured using micro-Ohm meter and Vickers microhardness tester. Results showed that AISI D2 tool steel treated with DCT-I cycle exhibited greater surface finish, hardness and dimensional stability compared to DCT-II cycle. It is mainly attributed to the greater precipitation of finer carbides and balancing of tensile-compressive residual stresses.