|Search for content and authors
Synchrotron investigations of non-uniformly shaped shot-peened samples
|Andrew M. Venter 1, Corrie La Grange 3, Felix Hofmann 2, Tea-sung Jun 2, Jonathan Belnoue 2, Rudolph Van Heerden 1, Alexander M. Korsunsky 2, Alexander Evans 4
1. Necsa Limited (NECSA), Church Street West Extension, Pretoria 0001, South Africa
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.
Presentation: Poster at 11th European Powder Diffraction Conference, Poster session, by Andrew M. Venter
See On-line Journal of 11th European Powder Diffraction Conference
Submitted: 2008-04-25 15:45 Revised: 2009-06-07 00:48