WEAR RESISTANT HIGH CHROMIUM CAST IRON AND WEAR RESISTANT MEMBER EXCELLENT IN FATIGUE CRACK PROPAGATING RESISTANCE AND PRODUCTION OF THE MEMBER

摘要

PROBLEM TO BE SOLVED: To reduce the tensile stress causing the propagation of fatigue cracks in high Cr cast iron and to prevent cracks therein by regulating the ratio of the content of Cr to the content of C and the product of the content of Mn and the content of Mo in high Cr cast iron contg. C, Mn, Cr and Mo to specified ranges. ;SOLUTION: In high Cr cast iron contg. C, Mn, Cr and Mo, the inequality of 5.0≤[Cr]/[C]≤7.2 ([Cr] and [C] denote each content) and the inequality of 1.8≤[Mn].[Mo]≤2.5 ([Mn] and [Mo] denote each content) are satisfied. The maximum value of the Vickers hardness obtd. at the inside of ≥20 mm from the surface of the member is higher than the Vickers hardness on the surface of the member other than a decarburized layer by ≥20. Moreover, at the time of the production, when quenching is executed from 850 to 1020°C quenching temp., the cooling rate at the inside of ≥20 mm from the surface of the member is regulated to ≤0.5°C/sec to precipitate carbides, by which the Ms point at the inside is increased, and the tensile residual stress in the surface of the member after the completion of heat treatment is reduced.;COPYRIGHT: (C)1999,JPO