Improving the cycle fatigue life of spring steel by a novel thermal cycling process

Abstract

A novel thermal cycling process was applied on the 65Mn spring to improve the cycle fatigue life. Results demonstrate that the cycle fatigue life after the thermal cycling process was improved from 3 times to 14 times, with an improvement of 470%. The fine, equiaxed grains were observed on the fracture surface. Moreover, the prolongation of cracks was prevented by the high density of interfaces, and the slipping and rotating between the grains consumed the applied energy during the cycling process, contributing to the improvement of cycle fatigue life.

Keywords

• structural
• fatigue
• thermal cycling process
• fracture mechanism