Low cycle torsional fatigue strength and excellent skin hardened steel shaft

摘要

PROBLEM TO BE SOLVED: To provide an inexpensive case hardening steel for shaft component which is excellent in workability and low cycle twisting fatigue strength in particular without using elements such as Ni and Mo and special alloy elements as much as possible and without being restricted by production conditions for steel and parts.;SOLUTION: The case hardening steel for shaft, whioch is excellent in workability and low cycle twisting fatigue strength, has a composition containing, by mass, 0.10 to 0.35% C, 0.35 to 1% Si, 0.2 to 0.6% Mn, ≤0.03% P, ≤0.03% S, 1.2 to 3% Cr, 0.01 to 0.2% Ti, 0.01 to 0.2% Nb, 0.0001 to 0.005% B and ≤0.015% N, and the balance Fe with inevitable impurities, and, in a Jominy edge hardening process, whose J9 hardness satisfies 35 to 50 HRC and whose J13 hardness satisfies 30 to 45 HRC. The case hardening steel is used by being subjected to carburizing-quenching-tempering.;COPYRIGHT: (C)2010,JPO&INPIT