EFFECTS OF BENDING IN BRASS ROCKWELL B SCALE TEST BLOCKS

Samuel Low, James Fink

Abstract

As part of a project to produce primary hardness reference blocks for the Rockwell B hardness scale at the National Institute of Standards and Technology (NIST), studies were conducted to observe the stability of the hardness value of the blocks over a period of time and with use. A study of brass test blocks at the 42 HRBW level revealed some interesting instability results when tested using the NIST standardizing machine with it’s large diameter sample support. <br />After a relatively small number of indentations, each block exhibited an abrupt change in the apparent hardness of the test block. Examination of this phenomena revealed that the abrupt change in hardness was the result of a combination of the bending of the block and the use of the NIST machine’s large diameter flat anvil. This paper discusses the reasons that block bending affects the hardness measurement.

Keywords

bending, Rockwell hardness, test block

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PWC-2003-TC5-015.pdf

DOI

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IMEKO TC

TC5 - Hardness Measurement

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