FATIGUE BEHAVIOR OF CARBURIZED STEEL BEFORE CRACK INITIATION

The fatigue behavior of quenched plus tempered carburized steel before crack initiation has been observed in tension-tension fatigue tests.It was found that fatigue softening and fatigue hardening coexist in this steel.A transition region near the ease depth of the steel divides the cross section of a round speeimen into two parts:the softened part outwards and the hardened part inwards.The degree of fatigue softening in the case and fatigue hardening in the core is increased with the maximum applied cyclic stress and the number of cycles.