Author(s)

N. Kawagoishi, T. Nagano & M. Moriyama

Abstract

Effect of shot peening on fatigue strength of maraging steel N. ~awa~oishi', T. ~ a ~ a n o ~ & M. o r i ~ a r n a ~ I Faculty of Engineering, Kagoshima University, Kagoshima, Japan 2 Miyakonojyo National College of Technology, Miyakonojyo, Japan Abstract Rotating bendmg fatigue tests were carried out for a shot-peened maraging steel in order to investigate the effects of shot peening on the fatigue strength and the fracture mechanism focusing on the effect of surface roughness. Fatigue strength was markedly improved by shot peening because of hardening and generation of compressive residual stress in the surface layer. The origin of fatigue fracture changed from the specimen surface at high stress levels to an inclusion in the interior of specimen at low stress levels. And at the middle stress levels, both fracture modes were observed. Consequently, the shape of the S-N curve of shotpeened specimen was complex, corresponding to the change of fracture mode. In the region where surface fracture

Keywords