1983 年 32 巻 361 号 p. 1132-1136
Torsional fatigue tests were conducted on induction hardened steel samples with various case depths to evaluate the relation between case depth and fatigue strength. Smooth specimens of 24mm in diameter were used and the optimum case depth for torsional fatigue strength was 7mm.
The site of origin of fatigue fracture was found to change from the case/core boundary to the surface at 7mm in case depth.