A Practical Method for Measuring Residual Stress Distribution by XRD after Needle or Hammer Peening: Application to a Simple Case
Ultrasonic needle peening (UNP) is a post-weld high frequency mechanical impact (HFMI) treatment process. This study describes a practical method for measuring residual stress (RS) distribution after UNP and its application to a simple case. Laboratory sin²ψ XRD RS analysis is performed on an UNP single-track on a flat structural steel specimen. This situation is studied as a reference case to characterize RS creation during UNP. It is demonstrated that successive mechanical and electrochemical polishing stages combined with relatively high resolution sin²ψ XRD measurement permits to get an effective surface and in-depth characterization of longitudinal and transverse RS around the UNP groove. High magnitude longitudinal compressive RS are found in the middle of the groove whereas transverse RS compression peaks are located on both sides of the groove. Discussion is conducted about sources of error associated with the experimental method and outlook for UNP process fundamental characterization.
Thomas Holden, Tamas Ungar, Thomas Buslaps and Thilo Pirling
R. Frappier et al., "A Practical Method for Measuring Residual Stress Distribution by XRD after Needle or Hammer Peening: Application to a Simple Case", Materials Science Forum, Vol. 905, pp. 91-100, 2017