40CrNiMoA钢模具用淬火一回火工艺对残余应力与裂纹敏感性的影响分析

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中图分类号：TG76 文献标志码：A

Abstract： This paper focuses on the problem that 4OCrNiMoA steel molds are prone to residual stress and cracks during heat treatment， and explores the influence of different quenchingtempering processes on their residual stress and crack sensitivity. A combined experiment was designed with quenching at 840，860，and 880∘C respectively，combined with tempering at 400，500，and 600∘C . By means of metallographic analysis，microhardness testing，X-ray diffraction residual stress measurement，and impact fracture observation，the efect of process parameters on microstructure evolution， mechanical properties，and fracture behavior was analyzed. The results show that when the quenching temperature is too high，such as 880∘C ， martensite coarsening occurs， the surface residual tensile stress is as high as 465MPa ，the impactenergy is only 43.7 J，and the crack sensitivity is significantly enhanced. When quenching at 860∘C and tempering at 500∘C ，the residual stress drops to 186MPa ，the hardness is maintained at 442HV ，and the impact energy reaches 82. 3J. At this time，the structure is uniform， the crack propagation resistance is the largest，and the comprehensive performance is the best. The study shows that reasonable control of quenching temperature and ensuring sufficient tempering can effectively coordinate strength and toughness and reduce the risk of cracking.

Key words： 4OCrNiMoA steel； quenching-tempering process；residual stress；crack sensitivity; microstructure

0 引言

在现代工业制造中，模具是成型工艺的关键部件，在汽车、航空航天、机械加工及精密制造等领域被大量应用。（剩余8355字）