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在生产实践中常见的磨削裂纹,无论是在磨削过程中使马氏体回火,引起表面体积收缩导致开裂,还是磨削不当,表面灼热冷却不良形成二次马氏体导致开裂,均有共同的特征:裂纹很细很长。 本故障实例为内燃机用6135活塞销,经磁粉探伤后端面发现裂纹。裂纹纵深超过常见磨裂的深度,其余特征与淬火裂纹很难区别。我们在金相分析的基础上借助显微硬度测试,较快地证实了确系磨削裂纹。
Common in the production of grinding cracks, both in the grinding process so that the martensite tempering, causing the surface volume contraction lead to cracking, or grinding improper cooling of the surface of poor cooling secondary martensite lead to cracking, both Have the same characteristics: the crack is very thin and long. An example of this fault is the 6135 piston pin for an internal combustion engine, which is cracked on the end face after magnetic particle inspection. Crack depth exceeds the depth of the common ground, the remaining features and harden the crack is difficult to distinguish. Based on the metallographic analysis, we used the microhardness test to quickly confirm the exact grinding crack.