Impact of Original Micro-Structure on Grind-Hardened Layer of 42CrMo Steel in Grind-Hardening

摘要

The grind-hardening test of 42CrMo steel was carried out on a forming grinding machine. The macrostructure, microstructures, micro-hardness and the depth of the hardened layer were measured and analyzed by optical micro-scope, scanning electron microscope and digital micro-hardness tester. The influences of original microstructure on the grind-hardened layer of 42CrMo steel were studied. The results show that the acicular martensite and a small amount of undissolved carbide appear in the surface layer, and slightly coarse martensite and a small amount of undissolved carbide appear in the middle layer of the completely hardened zone. Microstructure of the transitional zone varies with original structure. The microstructures and micro-hardness of the completely hardened zone have no obvious change under different original organizations, and the micro-hardness is 620HV0.5-700HV0.5. However, the distance from the slightly coarse martensite and the depth of the hardened layer increase with the uniformity improvement of the original microstructure.