Influence of Laser Peening on the Fatigue Strength of 3D Additive Manufactured Maraging Steel

Abstract

The purpose of this study is to investigate the effectiveness of laser peening (LP) on the fatigue strength of 3D additive manufactured maraging steel. First, LP was performed under several conditions and the optimum condition for improving fatigue strength were determined. Compressive residual stresses of 1100 MPa could be introduced on the surface by LP under the optimum condition. Then, bending fatigue tests were conducted using the two types of specimens; one with laser peened specimens under the optimal conditions (LP specimen) and the other without LP (Non-LP specimen). As a result, it was found that the fatigue strength of the LP specimen was about 43% higher than that of the Non-LP specimen. This result indicates that the introduction of compressive residual stress by LP improves the fatigue strength of 3D additive manufactured maraging steels. In addition, the fracture surfaces of specimens were observed and the fracture mechanism was investigated.