ASTM B933 – Standard Test Method for Microindentation Hardness of Powder Metallurgy (PM) Materials
Significance and Use
5.1 Microindentation hardness testing provides a measure of the hardness of the microstructural constituents of a porous material. It indicates the hardness the material would have if there were no pores present and the material was tested using macroindentation hardness methods. Loads are limited to a maximum of 200 gf to reduce the likelihood of interference from the porosity.
5.2 Microindentation hardness tests allow the evaluation of specific phases, microstructural constituents, and regions or gradients too small for macroindentation hardness testing.
1.1 This test method covers the determination of the microindentation hardness of powder metallurgy (PM) materials. The test method differs from the approach used for pore-free materials in terms of the precautions required to deal with the porosity.
1.2 This procedure covers tests made with the Knoop or Vickers indenters under loads in the range from 1 to 200 gf.
1.3 Automated testing is not generally suitable for use with porous PM materials, because acceptable indentations require avoiding placing indentations in the immediate vicinity of a pore, a condition not guaranteed with automated placement of the indentations. Any automated testing shall allow for review of indentations post-test to reject any distorted or unusually large indentations in accordance with 9.4.
1.4 A method for converting the directly measured indentation lengths to other hardness scales, for example, HRC is described in Appendix X1.