Evaluation of Residual Stress Distribution of Shot-Peened Spring by Positron Annihilation Spectroscopy

Author:  Yoshihiro Watanabe, Kanehisa Hattori, Naoya Uesugi, Yoshinori Kobayashi, Masato Yamawaki
Source:  ICSP-13
Doc ID:  2017033
Year of Publication:  2017
Abstract:  
Introduction: Shot peening is widely used for surface-treating of spring parts as a powerful method to enhance the fatigue durability. The effect of shot peening is usually evaluated by the X-ray diffraction, but the repeatable electrochemical polishing should be required to measure the inner surface of shot peened parts. In order to increase the reliability of the treatment, a completely non-destructive inspection method is strongly required. Positron annihilation spectroscopy (PAS) has been used for probing lattice defects. By using PAS, it is possible to evaluate lattice defects, which is dislocation, induced by shot peening in the inner surface of a peened part non-destructively. In this study, we investigated the validity of PAS as a non-destructive inspection for shot peening for a coil spring specimens.