External Characteristics of Shot Peened Surfaces

Author:  Dr. David Kirk
Source:  The Shot Peener magazine, Vol 22 / Issue 4, Fall 2008
Doc ID:  2008037
Year of Publication:  2008
Abstract:  
Academic Study INTRODUCTION Shot peened components have two important external characteristics. These are: SURFACE ROUGHNESS and DIMPLE COVERAGE. Surface roughness depends mainly upon the size of shot used. There is a simple analogy with the use of emery papers. The coarser the grit size the rougher will be the final finish. Two-stage shot peening involves using a finer grade of shot after a coarser grade. That is equivalent to using a finer grade of emery after using a coarser grade. Average roughness is easily measured and is well understood. The commonest roughness parameter is Ra which is the average vertical deviation from some reference line. Measurement techniques can be either two-dimensional or three-dimensional and may involve either direct contact or noncontact sensors. Peening is normally applied as a final treatment. The change of surface roughness induced by shot peening will therefore depend on the initial roughness of the component