Stainless steel pipes generally use three Brinell, Rockwell, Vickers hardness indicators to measure their hardness.
Among the stainless steel pipe standards, Brinell hardness is the most widely used, and the hardness of the material is often expressed by the diameter of the indentation, which is intuitive and convenient. However, it is not suitable for steel pipes of harder or thinner steel.
The Rockwell hardness test of stainless steel pipes is the same as the Brinell hardness test. The difference is that it measures the depth of the indentation. The Rockwell hardness test is currently a widely used method, in which HRC uses the steel pipe standard after Brinell hardness HB. Rockwell hardness can be applied to the determination of extremely soft to extremely hard metal materials. It makes up for the Brinell method and is simpler than the Brinell method. It can read the hardness value directly from the dial of the hardness machine. However, because its indentation is small, the hardness value is not as accurate as the Brinell method.
The Vickers hardness test of stainless steel pipes is also an indentation test method that can be used to determine the hardness of very thin metal materials and surface layers. It has the main advantages of the Brinell and Rockwell methods, but overcomes their basic disadvantages, but it is not as simple as the Rockwell method, and the Vickers method is rarely used in steel pipe standards.
For stainless steel pipes with an inner diameter of more than 6.0mm and a wall thickness of less than 13mm, an annealed stainless steel pipe with a W-B75 type hardness tester can be used. It is very fast and simple to test and is suitable for fast and non-destructive qualification inspection of stainless steel pipes. Stainless steel pipes with inner diameter greater than 30mm and wall thickness greater than 1.2mm are tested for HRB and HRC hardness using Rockwell hardness tester. Stainless steel pipe with inner diameter greater than 30mm and wall thickness less than 1.2mm. The surface Rockwell hardness tester is used to test HRT or HRN hardness. For stainless steel tubes with inner diameters less than 0mm and greater than 4.8mm, the Rockwell hardness tester for pipes is used to test the HR15T hardness. When the inner diameter of the stainless steel pipe is greater than 26mm, the hardness of the inner wall of the pipe can also be tested with a Rockwell or surface Rockwell hardness tester.