Hardware shrapnel heat treatment classification and hardness requirements

1. Use a hardness tester to test the hardness of heat-treated workpieces. 　　PHR series portable surface Rockwell hardness tester is very suitable for testing the hardness of surface heat-treated workpieces, and can test various surface heat-treated workpieces with an effective depth of more than 0.1mm. The operation is simple, easy to use, low in price, and the hardness value can be read directly. 2. Surface heat treatment is divided into two categories. One is surface quenching and tempering heat treatment, and the other is chemical heat treatment. The hardness inspection method is as follows: Chemical heat treatment is to make the surface of the workpiece infiltrate the atoms of one or several chemical elements to change 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.　　3, the main technical parameters of the chemical heat treatment workpiece are the depth of the hardened layer and the surface hardness 　　 the depth of the hardened layer or the Vickers hardness tester. Detect the distance from the surface of the workpiece to the point where the hardness drops to 50HRC. This is that the surface hardness test of the effective hardening deep chemical heat treatment workpiece is similar to the hardness test of the surface hardening heat treatment workpiece. Both can be tested with a Vickers hardness tester, a surface Rockwell hardness tester or a Rockwell hardness tester, but the nitriding thickness is relatively thick. Thin, generally not more than 0.7mm, at this time Rockwell hardness tester can no longer be used. If the parts have high local hardness requirements, they can be locally quenched and heat treated by induction heating, etc. 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 tester 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.　　4. Surface quenching and tempering heat treatment is usually carried out by induction heating or flame heating. The main technical parameters are surface hardness, local hardness and effective hardened layer depth. Hardness testing can use Vickers hardness tester, Rockwell or surface Rockwell hardness tester can also be used. The choice of test force (scale) is related to the effective hardened layer depth and the surface hardness of the workpiece. There are three hardness testers involved here. The Vickers hardness tester is an important method for testing the surface hardness of heat-treated workpieces. It can choose a test force of 0.5-100kg to test the surface hardening layer as thin as 0.05mm. Its accuracy is the highest, and it can distinguish the tiny surface hardness of the workpiece. difference. In addition, the effective hardened layer depth must also be detected by a Vickers hardness tester. Therefore, it is necessary to equip a Vickers hardness tester for units that perform surface heat treatment processing or use a large number of surface heat treatment workpieces.　　5. The surface Rockwell hardness tester is also very suitable for testing the hardness of surface quenched workpieces. The surface Rockwell hardness tester has three scales to choose from. It can test various surface hardened workpieces whose effective hardening depth exceeds 0.1mm. Although the accuracy of the surface Rockwell hardness tester is not as high as that of the Vickers hardness tester, it has been able to meet the requirements as a means of quality management and qualification inspection for heat treatment plants. Moreover, it also has the characteristics of simple operation, convenient use, low price, rapid measurement, and direct reading of the hardness value. The surface Rockwell hardness tester can be used to quickly and non-destructively test batches of surface heat-treated workpieces. This is of great significance to metal processing and machinery manufacturing plants. When the surface heat treatment hardened layer is thick, Rockwell hardness tester can also be used. When the thickness of the hardened layer is between 0.4 and 0.8mm, the HRA scale can be used, and when the thickness of the hardened layer exceeds 0.8mm, the HRC scale can be used.　　6. u200bu200bConversion table　　 The three hardness values u200bu200bof Vickers, Rockwell and Surface Rockwell can be easily converted to each other and converted into the hardness value required by standards, drawings or users. The corresponding conversion table has been given in the international standard ISO, the American standard ASTM and the Chinese standard GB/T.