Hardness Testing in Investment Casting Hardness is one of the metallic properties of castings and is defined as the ability to resist permanent mechanical deformation. Hardness testing is a quality test used by foundries to measure the characteristics of cast metals and their suitability for different applications. Its popularity is due to the non-destructive nature of the test and its relationship to other mechanical properties. https://www.jccasting.com/blog/what-is-hardness-testing-in-investment-casting/