Novel System for Potential Non-destructive Material Inspection Using Positron Annihilation Spectroscopy on Shot Peened parts

Author:  Y. Watanabe, K. Hattori, M. Yamawaki, Y. Kobayashi,and K. lto
Source:  Conf Proc 2014: ICSP-12 Goslar, Germany (pgs.293-298)
Doc ID:  2014092
Year of Publication:  2014
Abstract:  
Shot peening is widely used for surface-treating of automotive and aerospace parts as a powerful method to enhance the fatigue durability. The efficacy of shot peening is usually evaluated by the X-ray diffraction, but this method is destructive. In order to increase the reliability of the treatment in various fields, a completely non-destructive method is strongly required. A new positron annihilation spectrometer, consisting of a radioactive-²²Na (²²NaCl) positron source sealed between two thin films, a Ge gamma ray detector and an accompanying digital spectrometer, was developed for measurement system of shot peening effects. By using this system, positron annihilation gamma ray spectra for several shot peened materials including the inner surface of pipes were measured and the shape of the gamma ray spectra was analyzed as the line-shape (S) parameter. A good relationship between the S parameter and residual compressive stress profile was obtained.