Hardness test of erw pipe

The surface quenching and tempering heat treatment of erw pipe 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 be performed using a Vickers hardness tester, a Rockwell hardness tester, or a Superficial Rockwell hardness tester. The selection of the test force (scale) is related to the depth of the effective hardened layer and the surface hardness of the ERW pipe.

The Vickers hardness tester is an important means to detect the surface hardness of the heat-treated ERW steel pipe. It can test the surfacing layer as thin as 0.05mm thick, and the test force is 0.5-100kg. Highest precision, able to distinguish the surface hardness of heat-treated workpieces. small difference. In addition, the depth of the effective hardened layer is also detected with a Vickers hardness tester. Therefore, for units that carry out surface heat treatment or use a large number of surface heat treated ERW steel pipes, it is necessary to use a Vickers hardness tester.

Superficial Rockwell hardness testers are also well suited for testing the hardness of case-hardened workpieces. The Superficial Rockwell Hardness Tester offers three scales. Various surface hardened ERW steel pipes with effective hardening depth exceeding 0.1mm can be tested. Although the accuracy of the surface Rockwell hardness tester is not as high as that of the Vickers hardness tester, it can meet the requirements as a detection method for quality management and qualification inspection of heat treatment plants. In addition, it also has the characteristics of simple operation, convenient use, low price, fast measurement speed, and direct reading of hardness value. Using the surface Rockwell hardness tester, a batch of ERW steel pipes with surface heat treatment can be quickly and non-destructively tested one by one.

When the surface heat treatment hardened layer is thick, the Rockwell hardness tester can also be used. When the heat treatment hardened layer thickness is 0.4-0.8mm, the HRA scale can be used, and when the hardened layer thickness exceeds 0.8mm, the HRC scale can be used.

The three hardness values of Vickers, Rockwell and Superficial Rockwell can be conveniently converted into each other and converted into hardness values required by standards, drawings or users. The corresponding conversion tables are given in the international standard ISO, the American standard ASTM and the Chinese standard GB/T.

If the local hardness of the part is high, induction heating can be used for local quenching heat treatment. For this type of ERW steel pipe, the position and local hardness value of local quenching heat treatment are usually marked on the drawing. The hardness test of erw steel pipe should be carried out in a designated area. Hardness tester can use Rockwell hardness tester to test HRC hardness value. If the heat treatment hardened layer is shallow, the HRN hardness value can be measured with a surface Rockwell hardness tester.

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