hardness
Stainless steel pipes generally use three hardness indicators: Brinell, Rockwell, and Vickers to measure their hardness.
Brinell hardness
Among stainless steel pipe standards, Brinell hardness is the most widely used. The indentation diameter is often used to express the hardness of the material, which is both intuitive and convenient. But it is not suitable for 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, which is an indentation test method. The difference is that it measures the depth of the indentation. Rockwell hardness test is currently a widely used method, among which HRC is used in steel pipe standards second only to Brinell hardness HB. Rockwell hardness can be used to measure metal materials from extremely soft to extremely hard. It makes up for the shortcomings of the Brinell method. It is simpler than the Brinell method and the hardness value can be read directly from the dial of the hardness machine. However, due to its small indentation, the hardness value is not as accurate as the Brinell method.
Vickers hardness
The Vickers hardness test of stainless steel pipe 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 Brinell and Rockwell methods and overcomes their basic shortcomings, but it is not as simple as Rockwell method. Vickers method is rarely used in steel pipe standards.
Hardness testing
For annealed stainless steel pipes with an inner diameter of more than 6.0 mm and a wall thickness of less than 13 mm, the W-B75 Webster hardness tester can be used. The test is very fast and simple, and is suitable for rapid and non-destructive qualification inspection of stainless steel pipes. For stainless steel pipes with an inner diameter greater than 30mm and a wall thickness greater than 1.2mm, use a Rockwell hardness tester to test HRB and HRC hardness. For stainless steel pipes with an inner diameter greater than 30mm and a wall thickness less than 1.2mm, use a surface Rockwell hardness tester to test the HRT or HRN hardness. For stainless steel pipes with an inner diameter less than 0mm and greater than 4.8mm, use a special Rockwell hardness tester for pipes 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.
