Papers by Keyword: Depth of Hardened Layer

Abstract: 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.

Abstract: We had done the two-pass grind-hardening experiment on 40Cr steel using the conventional aluminum grinding wheel on a surface grinder, compared the structure and performance of the hardened layer of one-pass grinding with those of two-pass grinding and analyzed the forming mechanism of two-pass grinding hardened layers. The results show that there are a similar martensite structure and change rules of hardened layer of one-pass grinding and two-pass grinding in spite of the different of initial structures, for martensite has tempered by the action of the creep feed grinding temperature field. The depths of hardened layer, microhardness and wear resistance have further improved, but the maximal compressive residual stress and its influencing depth of hardened layer have decreased. The forming mechanism of the two-pass grinding hardened layer is the same as that of the grinding hardened layer of quenched steel.