Hardness indicates the ability of the material to resist hard objects to the surface. It is one of the important properties of metallic materials. The higher the general hardness, the better the wear resistance. Commonly used hardness indicators are the hardness of the hardness, hardness and hardness of Vivtorinox.
1.Brinell hardness(HB):Put a certain size (diameter is 10mm) of steel ball into the surface of the material under a certain load (usually 3000kg) for a period of time,then get rid of loading,the ratio of load and area of indentation, the Brinell hardness value (HB) with unit of Kilograms force/mm2 (N/mm2).
2.Rockwell hardness(HR):When the HB>450 or the sample is too small, it can not use Brinell test but adopt rockwell hardness. Put diamond cone with a 120 degree angle or the steel ball with diameter of 1.59 3.18mm into the surface of measured material under load pressure. Then get the hardness by the indentation depth .
According to the test the hardness of the material , there are three different scale to show:
HRA: is the use of 60kg load and diamond cone pressing device obtained for high hardness, hardness of materials (such as hard alloy).
HRB: is the use of 100kg load and the diameter of 1.58mm steel quenched, the hardness for the lower hardness of the material (such as annealing steel and cast iron etc.).
HRC: is the use of 150kg load and diamond cone pressure to obtain the hardness of the material for high hardness (such as quenching steel, etc.).
3.Vickers hardness(HV):Put a load within 120kgs and Diamond pyramid with angle 136 degrees into the surface of material, Surface area of indentation pit of materials divide load,then will get vickers hardness.
Hardness test is one of the most simple and easy test method in mechanical performance test. In order to be able to use the hardness test to replace some mechanical performance test, production needs a more accurate hardness and strength of the conversion relationship.Practice has proved that the hardness value and strength value of all kinds of hardness of metal materials have a similar relationship. Because the hardness value is determined by the initial plastic deformation resistance and the resistance to plastic deformation resistance, the higher the strength of the material, the higher the plastic deformation resistance, the higher the hardness value is.