Hardness Testing Techniques for Fasteners
Hardness defines how a material resists permanent deformations such as indentation. Because measuring this characteristic is a mature technology, several hardness methods are available that produce different hardness values. Parts like fasteners are typically tested at heat treatment to affect the process and the outcome. However, these tests are also conducted on raw materials for high-strength fasteners or some coating finishes. Advantages of Hardness Testing Such tests are quick and easy, relatively inexpensive, and can work on finished components since they do not destroy the specimen, which can be of any size and shape, such as a fastener. In general, mechanical hardness tests rely on an indenter made of tough material, such as hardened steel, carbide, or diamond. It presses into the surface of the test component at a specific force. The hardness values come from either how deeply the indenter penetrates or the size of the indent with smaller indents signifying harder ma...