Advanced Materials Research Vols. 834-836

Abstract: The contact surface of a hinge suffers huge pressure in particularly bad lubrication conditions. Reinforced polymer bearing pads offers low friction under dry sliding conditions. Load transfer between contact surfaces was studied, showing that the pressure and positions are related to the power output of the loco. The friction coefficient of concave bearings with polymer pads was low, and would not totally failed in a high contact stress. Performances of polymer pads on loads were simulated, and provided a global analysis for the design of the pads.

Abstract: The microstructure of cement composite soil was studied with the scanning electron microscopy (SEM) experiment, the microcosmic mechanism of the strength increasing were tested in the lab with different additive quantity,different curing periods. The interaction of the cement composite soil with soil,water,cement grout were analyzed,the experimental results show that: the pumice to join makes the composite cement soil strength first increases then decreases, and there is an optimal dosage of 8%, along with the growth of the curing age, after 28 days, hydration reaction continues, cement composite soil age 60 days of gelling material than 28 days.

Abstract: Using the experimental method for water medium interval target how to affect the ability of the jet penetration degree is determined. In order to verify the target interval between target and target medium effect on the jet penetration, with a shaped charge respectively on the interval of air and water medium target penetration experiment, the experimental results show that water medium for jet penetration does exist more adverse effect than air. It is combined with numerical simulation and experimental results to revise penetration of traditional formula.

Abstract: The objective of this paper is to investigate the effects of solid-state phase transformation on welding residual stress in high stress low alloy steel. In this study, based on commercial finite element software, a sequentially coupled thermal, metallurgical, mechanical plane strain finite element model is developed. The main effort is to develop a series of subroutines which consider the heat transfer from welding arc and numerical implementation of a thermo-metallurgical-mechanical constitute equation. The effectiveness of developed computational method is confirmed by a butt welding simulation. Simulation of butt welding demonstrates that the distribution pattern of longitudinal residual stresses perpendicular to weld centerline at the upper surface of weldment has two peak and transformation plasticity has significant effect on the evolution of residual stress.

Abstract: With the development of environment-friendly cutting technology, the low-temperature MQL technology emerged. In order to solve the problem that caused by cutting heat, it adds the cold air on the foundation of MQL. In the view of low-temperature MQL studies which could reduce the cutting force and heat, we have done a lot of experiments. The experimental results show that the most important reason why the low-temperature MQL can reduce the cutting force effectively is a reliable lubricant film that between tool and chip. At the same time, the cold air take away a large amount of heat thereby is reducing the temperature of the tool, so that extending the tools service life.

Abstract: This paper summarizes the rubber component's fatigue life research methods, mainly includes the crack nucleation method, the crack propagation method and the S-N curve method, sums up the these methods from different angels of fatigue life, and various methods based on the choices are given; Based on the working conditions and fatigue failure evaluation criteria to choose the appropriate design calculation method, in order to achieve relatively accurate results of fatigue life prediction and simplify the calculation, and separately summarized FEM used in the rubber fatigue life on the application and progress in the recent stage.

Abstract: With the development of miniaturization and lead free of electronic products, high demand is put forward about solder. AuSn20 lead free solder is widely used in high reliable hermetic package and die welding due to excellent mechanical property. This paper described the proper ties and preparation technology of AuSn20 solder, pointed out the disadvantages of the conventional drawing and rolling process, casting process and laminose composite process of cold rolling, put out improvement of study method and the preparation technology, investigate and develop the new forming technology for preparing AuSn20 low temperature eutectic solder, will achieve the solid basis for the large-scale production of this material.

Abstract: Impact of sample preparation on determination of hydrogen content in TC4 titanium alloys is studied through the experimental test method which was developed according to ASTM E 1447-2009. The simulation of the heating process in sample preparation process verifies the slight warming (60°C ~ 80 °C) will affect the test result of hydrogen content in TC4 titanium alloys. The heating process makes the result be lower than the actual content.

Abstract: The study is diffusion bonding of Mg-AZ31 and Al-6061 under pressure and no pressure by using the direct bonding method. After bonding process, characteristics phase in interface and bonding boundaries of Mg-AZ31/Al-6061 were characterized . The diffusion formation was observed by SEM. Aluminum solid solution and Mg₁₇Al₁₂ alloy phase was proved by analysis of XRD. In the process of measurement, crystalline structure of nearby interface characteristics phase was analyzed in detail by TEM. Based on the above analysis, the crystal model of the magnesium alloy and aluminum alloys was established under pressure, and the bonding mechanism was discussed. The results show that the bonding materials could be bonded under no pressure and the structure of bonding interface is more optimized than pressure.

Abstract: The tensile and impact properties of SAE4320 and SAE8620 alloys were investigated. Various heat treatments were applied to these two alloys, including different pre-heat treatment. The results shown that after Carburizing and Quenching, both SAE4320 and SAE8620 alloys were highly sensitively to V-notches for their impact samples. In any case, SAE4320 alloy revealed higher tensile strength, better impact toughness and deformation property. Previous work shown that after Carburizing and Quenching, the impact toughness of SAE8620 alloy was too low, the products made of it was very dangerous. Based on the results, a new advanced product was made of SAE4320 alloy instead of SAE8620 alloy. And the new product exhibited good properties. The impact value of the new product far exceeded the older products.