Characteristic of heat treatment and rolling contact fatigue of high speed cast steel containing high carbon

摘要

Fe-1.8 % C-Cr-Mo-W-V-Co alloys varying in 4% and 7% of vanadium content, 0% and 5% of cobalt content and 5% of each alloying element (Cr, Mo and W) were produced by casting. The characteristics of heat treatment with these alloys quenched andtempered were investigated and their rolling contact fatigue strength was studied. The quenching temperature at which the highest matrix hardness was obtained for quenched alloys became higher as the vanadium content was increased. Tempering at about 773K resulted in the secondary hardening of the alloys. The high vanadium alloy, which contained less plate-like or rod-like M{sub}2C carbides and more granular MC carbides, showed excellent rolling contact fatigue characteristics. Since the interfacebetween the carbides and matrix had many defects, binding force between the carbides and matrix was small and cracks propagated along the defective interface. Cracks also passed through plate-like or rod-like brittle M{sub}2C carbides which were highlysensitive to notch effects when they intersected the carbides.