Carbon steel hardness rockwell

Carbon steel hardness rockwell is an index for determining the hardness value by the depth of plastic deformation of the indentation, and 0.002 mm is used as a hardness unit. The use of different indenters and different test forces in the rockwell hardness test results in different combinations corresponding to different scales with Rockwell hardness. There are three rulers commonly used, and their applications cover almost all common metal materials.

Carbon steel hardness rockwell(HR) test, when the sample is too small or the Brinell hardness (HB) is greater than 450, it is measured by rockwell hardness. The test method is to use a diamond cone with a apex angle of 120 degrees or a steel ball with a diameter of 1.5875mm/3.175mm/ 6.35mm/12.7mm, and press it into the surface of the material to be tested under a certain load, and obtain the material from the depth of the indentation. Hardness. The three most commonly used scales are A, B, C, ie HRA, HRB, HRC. According to the hardness of the experimental materials, the scales with different hardness ranges are used to indicate:

HRA is a hardness obtained with a 60Kg load and a diamond cone indenter for higher hardness materials. For example: steel sheet, hard alloy.
HRB is a hardness obtained by using a 100Kg load and a 1.5875mm hardened steel ball for a material with a lower hardness. For example: mild steel, non-ferrous metals, annealed steel, etc.
HRC is a hardness obtained with a 150Kg load and a diamond cone indenter for higher hardness materials. For example: hardened steel, cast iron, etc.

Carbon steel hardness rockwell test requires a sample sample, the thickness of which cannot be less than 10 times the depth of the residual indentation, and no obvious deformation marks can appear on the back side of the sample. The thickness of the sample thus determines the choice of load, and the load must be such that the deformation caused by it is less than the minimum thickness of the sample. For each hardness test, there is a minimum measurable thickness.