Hardness test standard of workpiece after heat treatment

scratch hardness 

Indentation hardness

Rebound hardness (dynamic hardness, or hardness)

See hardness test.

The ability of a material to partially resist hard material pressing into its surface is called hardness. The common method to test the hardness of iron and steel is to file on the edge of the workpiece with a file, and judge the hardness by the depth of the scratch on the surface. This method is called file test, which is not very scientific. It is more accurate to use hardness testing machine to test hardness, which is a common method in modern hardness testing. Commonly used hardness testing methods include Brinell hardness, Rockwell hardness and Vickers hardness.

Hardness is an important performance index to measure the hardness and softness of metal materials. It can be understood as the ability of materials to resist elastic deformation, plastic deformation or damage, or the ability of materials to resist residual deformation and anti damage. Hardness is not a simple physical concept, but a comprehensive index of mechanical properties such as elasticity, plasticity, strength and toughness. Hardness test can be divided into static pressure method (such as Brinell hardness, Rockwell hardness, Vickers hardness, etc.), scratch method (such as Mohs hardness), rebound method (such as shore hardness), microhardness, high temperature hardness and other methods according to different test methods.

The Brinell hardness is expressed by HB [n (kgf / mm2)] (HBS \ HBW) (refer to GB / t231-1984). In production, the Brinell hardness method is commonly used to measure the hardness of the returned, normalized and tempered steel, as well as the hardness of cast iron, non-ferrous metals, low alloy structural steel and other rough or semi-finished products.

Rockwell hardness can be divided into four types: HRA, HRB, HRC and HRD. Their measuring range and application range are also different. Generally, HRC is widely used in production. The indentation is small, and the hardness of thin and hard materials and finished parts can be measured. Vickers hardness is represented by HV (refer to GB / t4340-1999), and the sample is measured.

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