Shot peening is an important surface impact treatment widely used in industry to improve the performance of metallic parts subjected to fatigue loading, contact (fretting) fatigue, stress corrosion and other damage mechanisms by inducing beneficial compressive residual stresses in the surface region. Residual stresses induced by shot-peening are not limited to the material surface regions, but may extend to depths of up to 1mm into steel, depending on the shot-peening intensity and the material properties.  The conditioning process is quantified using the ALMEN calibration method where a flat reference plate is simultaneously shot blasted in parallel to the sample being treated.  This verification procedure however does not take into account differing material geometries, surface properties and residual stresses existing in practical specimens due to their manufacture.  Direct quantification of the extent of the beneficial compressive residual stresses induced through the shot-peening process has become essential due to the occurrence of premature fatigue failures through cracking.  We report a quantitative assessment of the efficiency of shot-peening on conical samples treated at three different shot-peening intensities, compared to a water quenced (without shot peening conditioning), as well as a control sample (as reference).

Investigations were performed at the ID31 instrument on 2mm thick slices wire EDM cut from the respective bulk conically shaped 17-4PH stainless steel samples to facilitate transmission measurements at contant pathlength through the sample thickness as function of depth below the surface.  Results of the in-plane and surface normal components of residual strain  indicate significant differences between line scans taken at three locations from the tip, reflecting an underlying material thickness dependence.  An exploratory line scan taken at 3mm from the tip in the bulk of a conical sample indicates substantially larger compressive strains existing at the near surface region.  The latter indicates that significant relaxation of the residual strains had occurred due to the sectioning of the slices.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/15275 must be provided.

1. Synchrotron X-ray diffraction studies of products of the steel pipe corrosion measured in the native aqueous suspension
2. Structural characterization of a coarse-grained transparent silicon carbide powder by a combination of powder diffraction techniques