Hardness Testing Review

Engineering Metals and Materials Table of Contents

If the material type is known, a hardness test is a simple way to verify that a material has been properly heat-treated. Hardness testers such as Rockwell, Brinell, and Vickers can be useful to check metals for actual hardness.

Hardness tests are generally considered nondestructive, hardness testing does leave a small pit in the surface; therefore, hardness tests should not be used on sealing surfaces, fatigue critical parts, load bearing areas, etc., components which will be used in critical applications . These hardness tests provide a convenient means for determining, within reasonable limits, the tensile strength of steel. It has several limitations in that it is not suitable for very soft or very hard steels.

Hardness testing of aluminum alloys should be limited to distinguishing between annealed and heat-treated material of the same aluminum alloy. In hardness testing, the thickness and the edge distance of the specimen being tested are two factors that must be considered to avoid distortion of the metal. Several readings should be taken and the results averaged. In general, the higher the tensile strength, the greater its hardness.