The hardness of steel pipe

hardness

The hardness of stainless and carbon steel pipe is generally measured by Brinell, Rockwell and Vickers hardness indexes.

Brinell hardness

In the stainless steel pipe standards, Brinell hardness is the most widely used. The indentation diameter is often used to represent the hardness of the material, which is both intuitive and convenient. However, it is not applicable to steel pipes made of harder or thinner steel.

Rockwell hardness

The Rockwell hardness test of stainless steel pipe is the same as the Brinell hardness test. The difference is that it measures the depth of the indentation. Rockwell hardness test is a widely used method at present, and HRC is only inferior to Brinell hardness HB in steel pipe standards. Rockwell hardness can be used to measure metal materials from very soft to very hard. It makes up for the shortcomings of Brinell method, which is simpler than Brinell method. It can directly read the hardness value from the dial of the hardness machine. However, due to its small indentation, the hardness value is not as accurate as Brinell method.

Vickers hardness

Vickers hardness test of stainless steel pipe is also an indentation test method, which can be used to measure the hardness of very thin metal materials and surface layers. It has the main advantages of Brinell method and Rockwell method, but overcomes their basic disadvantages, but is not as simple as Rockwell method. Vickers method is rarely used in steel pipe standards.

Hardness test

For annealed stainless steel pipes with an inner diameter of more than 6.0mm and a wall thickness of less than 13mm, W-B75 Vickers hardness tester can be used. It is very fast and simple to test, and is suitable for rapid non-destructive qualification inspection of stainless steel pipes. For stainless steel pipes with inner diameter greater than 30mm and wall thickness greater than 1.2mm, Rockwell hardness tester shall be used to test the hardness of HRB and HRC. For stainless steel pipes with an inner diameter of more than 30mm and a wall thickness of less than 1.2mm, a surface Rockwell hardness tester is used to test the HRT or HRN hardness. For stainless steel pipes with an inner diameter less than 0mm and more than 4.8mm, the hardness of HR15T shall be tested with a special Rockwell hardness tester. When the inner diameter of stainless steel pipe is greater than 26mm, the hardness of the inner wall of the pipe can also be tested with Rockwell or surface Rockwell hardness tester.