Material hardness and hardness testing...

Material hardness and hardness testing Material hardness is the property of the material which enables it to resist plastic deformation, usually by penetration or by indentation. The term of hardness is also referred to stiffness or temper, or to resistance to bending, scratching, abrasion, or cutting. It is the property of a material, which gives it the ability to resist being permanently, deformed when a load is applied. The greater the hardness of the material, the greater the resistance it has to deformation. Hardness has been variously defined as resistance to local penetration, scratching, machining, wear or abrasion, and yielding. The multiplicity of definitions, and corresponding multiplicity of hardness measuring instruments, together with the lack of a fundamental definition, indicates that hardness may not be a fundamental property of a material, but rather a composite one including yield strength, work hardening, true tensile strength, modulus of elasticity, and others. In mineralogy, hardness is normally described as the resistance of a material to being scratched by another material. The ability of materials to resist scratching by another material can be ranked by referring to the Mohs scale which assesses relative hardness of the materials. In metallurgy hardness is defined as the ability of a material to resist plastic deformation. It is sometimes known as indentation hardness which is the resistance of a material to indentation. The usual type of hardness test is where a pointed or rounded indenter is pressed into a surface of the material under a substantially static load. Hardness measurement can be carried out at macro scale, micro scale or nano scale according to the forces applied and displacements obtained. Measurement of the macro hardness of the material is a quick and simple method of finding mechanical property data for the bulk...