How Accurate is Steel Media Hardness Testing?

Author:  Jack Champaigne, President Electronics Inc.
Source:  The Shot Peener magazine, Vol 25 / Issue 3, Summer 2011
Doc ID:  2011121
Year of Publication:  2011
Abstract:  
The Parting Shot by Jack Champaigne I was recently asked why there were variations among laboratory hardness reports for steel peening media. What I discovered in a brief investigation of the supplied reports was interesting and suggests that we need to pay attention to these findings. The hardness range of the sample is 45-52 HRc (Hardness Rockwell C scale). The accompanying illustrations indicate two areas of concern. First, there is a disparity among the laboratory results despite that all the labs were Nadcap accredited. Second, the sample had a higher hardness level than allowed in specifications.