Three kinds of hardness of stainless steel pipe fittings:
1. Rockwell hardness
The Rockwell hardness test of stainless steel pipe fittings 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. The Rockwell hardness test is currently a widely used method. Among them, HRC is second only to Brinell hardness HB in steel pipe standards. Extremely hard metal material, it makes up for the shortcomings of the Brinell method, which 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.
2. Brinell hardness
In the standards of stainless steel pipe fittings, Brinell hardness is the most widely used. The indentation diameter is often used to express the hardness of the material, which is intuitive and convenient, but it is not suitable for harder or thinner steel pipes.
3. Vickers hardness
The Vickers hardness test of stainless steel pipe fittings is also an indentation test method, which 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 is not as good as The Rockwell method is simple, and the Vickers method is rarely used in steel pipe standards.
4. Hardness testing
For annealed stainless steel pipes with an inner diameter of 6.0 mm or more and a wall thickness of 13 mm or less, the W-B75 Webster hardness tester can be used. It is very fast and easy to test, and is suitable for quick and non-destructive qualification inspection of stainless steel pipes. For stainless steel tubes with an inner diameter greater than 30mm and a wall thickness greater than 1.2mm, use a Rockwell hardness tester to test the hardness of HRB and HRC. 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 hardness of HRT or HRN. 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 hardness of HR15T , 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 superficial Rockwell hardness tester.