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Xu P.-Q.,Shanghai University of Engineering Science | Bao C.-M.,Shanghai University of Engineering Science | Bao C.-M.,Kolbenschmidt Pierburg Shanghai Nonferrous Components Co. | Lu F.-G.,Shanghai JiaoTong University | And 4 more authors.
International Journal of Advanced Manufacturing Technology | Year: 2011

In order to optimize the laser-tungsten inert arc (TIG) welding process of cemented carbide to steel, a novel combined model consisting of circular disk source, line source, and double ellipsoidal TIG heat source was put forward to simulate the deep penetration phenomena and bead profile. In contrast, laser heat source model was validated using macrostructure analysis results. The effects of the circular disk of radius and the material properties on the bead profile were discussed. For mechanism surface formation, surface depression or humps was discussed based on the high-speed photography technique to verify bead profile characterization. The results manifested that in the model, the circular disk radius played a key role in the formation of bead profile. And the penetration coefficient chiefly affected the root of weld and the keyhole formation. During the hybrid welding, the main forces influencing the surface depression or humping were intrinsic stress from coefficient of thermal expansion gradient, surface tension, buoyancy force, stirring action, and shock waves at the end of the keyhole. Before the solidification of the upper part of the melt, the melt was driven by the fluctuated plasma, plumes, or other forces. While the amount of melt filling the back welds metal of keyhole was larger than that caused by plume losses and the shrinkage of weld metal, the humps came into being. © 2010 Springer-Verlag London Limited. Source


Zou H.,Kolbenschmidt Pierburg Shanghai Nonferrous Components Co. | Cao X.,Kolbenschmidt Pierburg Shanghai Nonferrous Components Co. | Huang Y.,Shanghai Jinheli Wheel Co.
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2013

To improve mechanical properties of low pressure casting aluminum alloy wheels, Mg content in A356 aluminum alloy was modified slightly and T6 heat treatment process of A356 alloy was optimized to improve yield strength and elongation. Finally, impact resistance and fatigue resistance of the low pressure casting FA355 aluminum alloy wheel were improved. Source


Cao X.B.,Shanghai University | Cao X.B.,Kolbenschmidt Pierburg Shanghai Nonferrous Components Co. | Zhao J.,Shanghai University | Fan J.H.,Donghua University | And 3 more authors.
International Journal of Cast Metals Research | Year: 2014

The fatigue behaviour of A356 cast aluminium alloy under 104 cycles was investigated by a servohydraulic machine at the temperature of 150°C. The specimens for the fully reversible tension compression tests were cut from cylinder head castings of automobile engines. The testing data were treated by S–N curve and the staircase method and the mean values of fatigue property coincided with each other by these two methods, though the data scattered with different casting defects. The fracture surfaces of fatigue specimens were examined by OM, SEM and EDS. It was found that in most of the specimens two or more fatigue crack initiations appeared at a fracture surface. Compared with casting defects such as oxide film, inclusion and blowhole, shrinkage porosity is more detrimental to the fatigue behaviour of aluminium alloy castings. © 2014 W. S. Maney & Son Ltd. Source


Zhang M.,Shanghai University | Zhang M.,Kolbenschmidt Pierburg Shanghai Nonferrous Components Co. | Cao X.,Shanghai University | Cao X.,Kolbenschmidt Pierburg Shanghai Nonferrous Components Co. | And 2 more authors.
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2012

Fatigue tests in terms of high cycle of 10 7 and low cycle of 10 5 at 150°C were carried out for the samples from gravity-casting C14 cylinder heads of AC4B aluminum alloy. The low cycle fatigue strength and high-cycle fatigue strength of AC4B aluminum alloy were presented by non-linear fitting and statistical method. The results show that high-cycle fatigue S-N curves follows second-order exponential decay form, meeting the "limited fatigue limit" condition, while low-cycle fatigue S-N curves is characterized by quadratic form. Low-cycle fatigue strength and high-cycle fatigue strength obtained are consistent by two kinds of ways, which shows that the analysis method is rational and reliable. Fatigue strengths of samples involving the low-cycle and high-cycle both meet the new Sail cars safety and reliability of Shanghai GM. Source

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