14th International Conference on Shot Peening

Compressive residual stress relaxation behavior of shot peened AISI4140 steel during first cycle of repeated loading

Motoaki Hayama and Jun Komotori

Keio University, Graduate School of Science and Technology, School of Integrated Design Engineering, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama-shi, Kanagawa, 223-8522, Japan, motohym@keio.jp

Keio University, Faculty of Science and Technology, Department of Mechanical Engineering, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama-shi, Kanagawa, 223-8522, Japan, komotori@mech.keio.ac.jp

Introduction

Compressive residual stress generated by shot peening improves the fatigue properties of steel. However, this compressive residual stress is relaxed during the fatigue process. The relaxation of residual stress occurs in the initial stages of fatigue life, particularly in the first cycle of repeated loading. Nonetheless, the behavior of residual stress relaxation during the first cycle of repeated loading has not yet been clarified.

Objectives

The aim of this study is to examine the relaxation behavior of the residual stress generated by shot peening during the first cycle of repeated loading, using an in-situ X-ray stress measurement [1], and to discuss a method to estimate the residual stress stability during the fatigue process.