Heat treatment classification and hardness testing method of bearing workpieces

The heat treatment hardness of the bearing workpiece is tested by a hardness tester. PHR series portable surface Rockwell hardness tester is very suitable for testing the hardness of surface heat treatment of workpieces, and can test various surface heat treatments of workpieces with an effective depth of more than 0.1mm. It is simple operation, convenient use, low price, and the hardness value can be read directly.

Surface heat treatment is divided into two categories, one is surface quenching and tempering heat treatment, which uses vibration absorption or vibration isolation devices to reduce or isolate bearing noise, and the other is chemical heat treatment.

Hardness inspection method 

Chemical heat treatment is to make the surface of the workpiece infiltrate the atoms of one or several chemical elements, thereby changing the chemical composition, organization and performance of the surface of the workpiece. After quenching and low temperature tempering, the surface of the workpiece has high hardness, wear resistance and contact fatigue strength, and the core of the workpiece has high strength and toughness.

The main technical parameters of the chemical heat treatment workpieces are the depth of the hardened layer and the surface hardness. The depth of the hardened layer still needs to be tested by a Vickers hardness tester. The surface hardness of the workpiece down to 50HRCd, the measured distance from deep layer to the surface, is the effective hardening depth.

The surface hardness test value of the chemical heat treatment workpiece is similar to the hardness test result of the surface hardening heat treatment workpiece. Generally, the rolling bearing noise generated from the bearing itself can be tested by a Vickers hardness tester, a surface Rockwell hardness tester or a Rockwell hardness tester, only when the thickness of nitriding layer is thinner, (usually not more than 0.7mm), then do not use Rockwell hardness tester for testing.

If the local hardness of the bearing parts is required to be high, the local quenching heat treatment can be carried out by induction heating and other methods. Such parts are usually marked on the drawing with the location of the local quenching heat treatment and the local hardness value. The hardness test of the parts should be carried out in the designated area. The hardness testing instrument can use Rockwell hardness tester to test the HRC hardness value. If the heat-treated hardened layer is shallow, the surface Rockwell hardness tester can be used to test the HRN hardness value.