Original paper(Vol.52 No.11 pp.1318)

Effect of Core Hardness and Case Depth on Low-Cycle-Impact-Fatigue Property in Carburized Steel

Masayuki HORIMOTO, Hitoshi MATSUMOTO, Taizo MAKINO, Nobuhiro MURAI, Kazuyuki ORITA, Yukio ARIMI, Satoshi FUJIKAWA and Takayuki NISHINO

Abstract:The objective of the present paper is to clarify the effect of the core hardness and the case depth of the carburized steel on low-cycle-impact fatigue strength, which is required for automotive differential gear. Low-cycle-impact bending fatigue tests for carburized steels were carried out. As a result, it was found that crack initiation life increased with increasing the core hardness and the case depth. Furthermore, change of crack initiation life can be explained by the change of strain range, which was dominated by the core hardness and the case depth, generated in the fillet of test specimen.

Key Words:Fatigue, Low cycle impact fatigue, Carburized steel, Core hardness, Depth of carburized layer, Differential gear