60Si2Mn钢壳体裂纹原因分析

目的查找某产品60Si2Mn钢关键零部件壳体,在冲压工序和超声波水浸探伤工序中,壳体底部存在裂纹疵病的原因。方法通过疵病部位宏观和微观观察、金相组织检查和验证试验等,检查壳体裂纹性质和原因。结论生产该壳体的原材料存在严重偏析现象,使壳体在热加工加热时,组织向奥氏体转变过程也产生差异,由于感应加热的时间相对较快,且感应加热时,钢材内外受感应磁场电流的不同大小的影响,内外组织变化产生不均匀性,导致在冲压过程中变形不一致,是壳体底部裂纹产生的原因。采取对壳体放慢加速度,局部回火改为整体退火等措施,能有效控制裂纹的产生。经过500发生产验证,结果未发现裂纹疵病产生。

60Si2Mn Steel Shell Crack Reason Analysis

Objective The aim of the study is to find the causes of crack fault at the bottom of 60Si2Mn steel shell of the key parts in stamping process and the ultrasonic water immersion inspection process. Methods Through macro and micro observation, microstructure examination and verification test, the nature and reason of the shell crack were checked. Conclusion The results showed serious segregation phenomenon in the raw material used to produce the shell, which led to difference in the transformation to the austenite during heating in the hot processing. The relatively fast induction heating, the effects of the different size of the induced magnetic field current on the inside and outside of the steel, and the resulting inhomogeneity in the organization change of the inside and outside parts as well as the inconsistent deformation in the process of stamping, were the causes of crack at the bottom of the shell. Slow acceleration of the shell, and whole annealing instead of local tempering, can effectively control the generation of cracks. No crack fault was found after 500 rounds of production verification.