The concept of material hardness

    Hardness is a performance index to measure the degree of hardness and softness of solid materials.Solid state metal materials have hardness, and nonmetallic solid materials have hardness, and nonmetallic solid materials also have hardness, diamond is the hardest of all solid materials.For metallic materials, hardness can sensitively reflect the differences of the metal materials in chemical composition, incense structure and heat treatment process.In the engineering and mechanical metallurgy industries, people can calculate other thermodynamic properties and fracture properties of metal materials by simple hardness tests and empirical formulas.Hardness testing has also been widely used in material research.Therefore, hardness test has become one of the indispensable means to test product quality, develop materials and determine reasonable processing technology.

    Hardness actually refers to a small or very small volume of solid material surface resistance to elastic deformation, plastic deformation or a resistance to hard crack.Therefore, hardness is not a simple and definite physical quantity, but a comprehensive performance index composed of a series of different mechanical properties such as elasticity, plasticity and toughness of materials.Therefore, the amount of hardness not only depends on the hardness itself, but also depends on the test method and test conditions.

    Significance of hardness testing of metallic materials

    The physical meaning of hardness is determined by its testing method and the relationship between strength and plasticity or fracture index.Hardness refers to the resistance of a metal to deformation or fracture over a small area of its surface.

    Hardness test can not only measure the hardness of the material itself, but also other properties of the metal material. These properties are as follows:

        1. 1. Determine the elastic properties of materials by bouncing method.

        2. A small amount of plastic deformation resistance was measured by pressing method, and the performance similar to yield limit was obtained.

        3. A large amount of plastic deformation resistance is measured by the compression method, thus obtaining properties similar to the strength of the necked metal.

        4. Use crossed(crossed) the method measures the true tensile strength。

        5. The specific work of deformation was measured by bouncing method.

        6. The anisotropy of plastic deformation was measured by pressing and marking.

    Common metal hardness tester: micro Vickers hardness tester, Vickers hardness tester, Rockwell hardness tester, Brinell hardness.