Materials Science Forum Vol. 950

Abstract: This research work aimed to study an effect of interpass temperature on a wear resistance of a hard-faced weld metal on JIS-S50C carbon steel surface. The experimental results were found that the increase of the interpass temperature resulted in the increase of the grain size, the decrease of the hardness, and the decrease of wear resistance of the hard-face weld metal. Low interpass temperature affected to increase the residual stress inducing the cracking on the interface between the first weld metal layer and the base metal. Wear surface composed the crater and the groove wear traces that showed the different evidence of the failed off metal particles. The lower wear rate was found at the location where contained high amount of the reinforced elements such as chromium, silicon and manganese. The lowest weight loss of 0.89% could be obtained with an application of the optimum interpass temperature of 150 °C.

Abstract: In order to study the effect of temperature on the mechanical properties of H90 copper strip material, the H90 copper strip test pieces were heated to different temperatures (20~600 °C) for tensile test; the yield strength, tensile strength, elastic modulus and elongation of H90 copper strip at different temperatures were obtained. Based on the test results, the empirical models of yield strength, tensile strength, elastic modulus of H90 copper strip at high temperature were established; the test showed that, with the increase of temperature, the yield strength, tensile strength and elastic modulus of H90 copper strip decreased greatly, and the elongation after fracture first increased-decreased-increased at 20~600 °C. The study results in this paper provide basic material data for analyzing the effect of temperature on the continuous firing of firearms and other weapons.

Abstract: An optimization of a gas metal arc welding (GMAW) process parameter is currently investigated for producing a dissimilar SS400/SUS304 steels joint because a requirement of a sound joint with higher tensile strength. A gas shielding type is one of the important parameter because it could produce a good arc, protect the weld pool from atmosphere and so on. So, this research work aimed to study an effect of the shielding gas type on the mechanical properties of the dissimilar SS400/SUS304 steels butt joint. A relation between microstructure and the mechanical properties of the butt joint was also investigated and compared. The summarized results are as follows. The optimized shielding gas that produced a maximum tensile stregnth of 550 MPa was 95%Ar+5%N₂. Nitrogen gas that mixed to the shielding gas affected to decrease dendrite size and to increase the hardness and tensile strength of weld metal. Fracture characteristic of the joint produced by N₂ mixed gas showed a larger deformation at the location that was closely the fracture location that implied a ductile behavior. The dissimilar SUS304/SS400 metals joint showed a low hardness base metal, a higher hardness interface and a highest hardness weld metal.

Abstract: With the ever-increasing concern about the energy and environment crises, aluminum alloys are becoming increasingly desirable in the automotive, aerospace, construction and other related industries due to their high specific strength. Various heat-treatment–stamping integrated techniques have been invented to address the formability challenge of aluminum alloy sheets. Electric field affects the heat treatment process of aluminum alloys. In this paper, a device for application of electric field during the heat treatment was developed. The maximum dimensions of specimen are determined via observing the distortion of metal sheets after quenching in cool water. The high-temperature resistant pure nickel wire gains a high-voltage proof performance by wearing bowl-shaped porcelain tubes, and is used to connect electrodes to power supply. The high-voltage resistant mica plates are bolted together to fill the gap between the specimen and electrode. This device was then used in a common commercial furnace to study the effect of electric field applied during the heat treatment on mechanical properties of AA 6082 sheets. It is found that electric field could enhance mechanical properties of AA 6082. The application of electric field has a potential to lower the cost of heat-treatment–stamping integrated techniques.

Abstract: In order to obtain high performance magnesium alloy thick-walled tubes, the magnesium alloy ingot was extruded by hydrostatic shrinkage extrusion technology. Through a series of experiments, it was found that the magnesium alloy tube was not formed in the extrusion ratio that is smaller than 2.11 . Deform-3D software was used to simulate the tube forming process under different extrusion ratios. It was noting that at the condition of the extrusion ratio of 2.11, the equivalent stress and strain of the extruded tube at the fixed sizing zone were obviously unevenly distributed, which was disappeared with the increase of the extrusion ratio. Compared with the homogenized magnesium alloy , the yield strength, the tensile strength and the elongation were improved when the tensile test was carried out on the extruded magnesium alloy thick-walled tube. These results clearly showed that the mechanical properties of magnesium alloy tubes were improved after hydrostatic extrusion.

Abstract: A series of connection with screw fasteners were tested to study the behavior of cold-formed steel moment connection. The test specimens included hot-rolled parallel flange channels, cold-formed lipped C-Channels, and self-drilling self-fastening screws. Two different lipped C-Channels and a various number of screws per connection were used in this study. The moment-rotation behavior, rotational rigidity, and the connection capacity differed with the number of screws. The connection behaved as a pinned connection when 4 screws were used. However, local buckling was observed in the cold-formed steel sections near the connection when 8, 10 and 14 screws were used. The connection test results were compared with theoretical results calculated in accordance to the Australian Standards. None of the connection tested could achieve the moment capacity of the section connected.

Abstract: Statistical process control (SPC) technique has become more and more often used for manufacturing process improvement with understanding the process and detecting the process variation. This paper presents a study from a small enterprise classified as OEM supply elevator assembly parts. A process capability study is performed for cutting and drilling processes in order to verify the process capable of consistently meeting the required specification and delivering quality products since increasing a number of rework parts. Why-why analysis was used to identify the root cause and the principles of Poka Yoke and jig & fixture design were then applied by design a measure gauge for cutting and drilling processes. After improvement, the result shows that the Cpk of cutting process increase from 0.19 to 2.72 while Cpk of drilling process also increase from 0.36 to 4.50. Since the Cpk is greater than 1.3 this means that both two processes have a capable to produce the output meet specification.

Abstract: A two-step solvothermal method was employed to synthesize the Graphene/Fe₃O₄/BaTiO₃ (GFT). X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectra are used to observe the microstructure and magnetic properties of GFT, and the nanoparticles of Fe₃O₄ and BaTiO₃ were uniformly deposited on the surface of the graphene nanosheets. Then GFT filler and the silicone rubber were mixed to manufacture the electromagnetic shielding materials. The vector network analyzer was employed to evaluate the electromagnetic shielding effectiveness of the modified electromagnetic shielding materials. The influence of the mole ratio of the GFT constituents, the mass content of the filler on the electromagnetic shielding effectiveness was studied between 1 GHz and 20 GHz. It is shown that the GFT/silicone rubber has the best electromagnetic shielding effectiveness for 24:1:1 of graphene: Fe₃O₄: BaTiO₃ and 16 % GFT.

Abstract: Polyurethane foam has the properties of energy absorption and mitigating the impact, it has been used in internal protection head cap of cylindrical objects as cushion material, its theory and simulation has been widely discussed by the domestic and foreign scholars, but little experimental research is involved. In this paper, a dynamic loading water-entry impact experiment was designed for polyurethane foam plastics with different densities. In addition, ANSYS/LS-DYNA finite element analysis software was used to simulate water-entry process of cushion materials with different densities. The experimental and simulation results show that the 0.18 g/cm³ polyurethane material can effectively protect the cylindrical head, reduce the stress and have a good cushion effect on it.

Abstract: Microwave-assisted catalytic reductive dechlorination on Raney Ni-Al alloy catalyst is an efficient method for treatment of chlorobenzene (CB) and 1,4-dichlorobenzene (1,4-DCB). The result shows that the Raney Ni-Al alloy catalyst retains its high activity in this in-situ reductive dechlorination reaction. The reductive dechlorination reaction was in accordance of a psendo-second-order reaction kinetics under the microwave irradiation. The apparent reductive reaction rate constant of CB dechlorination was 0.0175 L/mol·min at 30°C and 0.114 L/ mol·min at 50°C, and the activation energy Ea was 76.24 kJ/mol. The reaction rate constant of 1,4-DCB dechlorination was 0.0376 L/ mol·min at 35 °C and 0.151 L/ mol·min at 50 °C, and the activation energy Ea was 76.66 kJ/mol. The dechlorination for CB and 1,4-DCB was rapid and complete under mild conditions. It shows that the microwave-assisted catalytic in-situ reductive dechlorination on Raney Ni-Al alloy catalyst is an effective method for dechlorination of polychlorinated organic compounds.