SEDL / STP / STP1057-EB / STP25269S

Operator Errors in the Measurement of Microindentation Hardness

Vander Voort, GF
Supervisor, Metal Physics Research, Carpenter Technology Corp., Reading, PA

Pages: 31    Published: Jan 1989

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Abstract

An interlaboratory test program (“round-robin”) was conducted by ASTM Committee E-4 on Metallography to develop information for a Precision and Bias section for ASTM Test Method for Microhardness of Materials (E 384). Knoop and Vickers indents were made by one person using seven specimens of varying hardness and six test loads: 25, 50, 100, 200, 500, and 1000 gf (five indents of each type at each load on each specimen). These indents were measured by personnel at 24 laboratories. The results demonstrate substantial variability in hardness which increased with decreasing test load and increasing specimen hardness, that is, with decreasing diagonal length.