레이저 피닝한 STS304의 무해화 균열 크기 평가

Abstract

This study evaluated the threshold stress intensity factor △Kth and fatigue limit σwc according to the micro crack length when micro crack exist in the STS304 steel. In addition, the compressive residual stress was introduced by fiber-delivered laser peening, and the harmless crack size (σhlm) was evaluated. Ando equation and Tange equation were used for evaluation. The threshold stress intensity factor and fatigue limit by the two equations were almost similar. The harmless crack size (σhlm) was similar even when evaluated by Ando and Tange equations. The harmless crack size (σhlm) was approximately a = 1.2 mm in the residual stress of the σx direction and approximately a = 1.25 mm in the residual stress of the σy direction.