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NIST Recommended Practice Guide: Rockwell Hardness Measurement of Metallic Materials



Samuel R. Low III


The Rockwell hardness test continues to be applied as a tool for assessing the properites of a product while the tolerances on the acceptable material hardness have become tighter and tighter. Adhering to good practice procedures when performing Rockwell hardness measurements and calibrations is a beneficial step to reducing measurement errors. The purpose of this Guide is to explain the causes of variability in Rockwell hardness test results and to supplenment the information given in test method standards with good practice recommendations. Although this Guide is directed more towards the users of Rockwell hardness having the greatest concern for accuracy in their measurements, much of the information given is also applicable to users that only require test results to be within wide tolerance bands, where high accuracy is not as critical.
Special Publication (NIST SP) - 960-5
Report Number


error, hardness, indentation, indenter, rockwell, standardization, test block, test method, verification


Low, S. (2001), NIST Recommended Practice Guide: Rockwell Hardness Measurement of Metallic Materials, Special Publication (NIST SP), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed April 24, 2024)
Created January 1, 2001, Updated February 24, 2009