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Study on forming mechanism of defects in metal injection molding of 42CrMo4 high strength structural parts |
CHEN Zhi-chao, ZHANG Peng, PENG Shi-min |
Shanghai Automobile Transmission Co., Ltd., Shanghai 201800, China |
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Abstract The formation mechanism of defects in the metal injection molding (MIM) process of ultra-high strength alloy 42CrMo4 steel was studied and discussed. The results show that the microstructure of the metal injection 42CrMo4 alloy contains a large number of pores and cracks, which are caused by bonding defects after supercooling due to the intersection of viscosity bodies during the injection process. During the degreasing process, the viscosity bodies cannot be completely fused, and the space among the powders form the boundary between the viscosity bodies. Under the condition of low sintering driving force, the defects are enlarged in the subsequent cooling shrinkage process to form internal holes and cracks.
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Received: 24 January 2018
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injection molding; viscosity body; sintering; crack; MIM |
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