The hardness and related testing methods of stainless steel weld tubes are basically the same as those of steel and other metals. Generally, Brinell, Rockwell, and Vickers hardness are commonly used to measure their hardness. The following is a detailed introduction by WENZHOU HUASHANG STEEL CO., LTD.
In the stainless steel weld tube fittings standard, Brinell hardness is widely used and is often represented by the indentation diameter to show the material's hardness, which is both intuitive and convenient. However, it is not suitable for harder or thinner steel pipes.
The Rockwell hardness test for stainless steel weld tubes is the same as the Brinell hardness test, which is an indentation test method. The difference is that it measures the height of the indentation. The Rockwell hardness test is currently widely used, and HRC is second only to Brinell hardness HB in the steel pipe standard. Rockwell hardness can be used to measure the hardness of metal materials from extremely soft to extremely hard. It makes up for the shortcomings of the Brinell method and is simpler than the Brinell method. The hardness value can be directly read from the hardness machine's dial. However, due to its small indentation, the hardness value is not as accurate as the Brinell method.
Stainless steel weld tube fittings Vickers hardness test is also an indentation test method, which can be used to measure the hardness of very thin metal materials and surface layer hardness. It has the main advantages of Brinell and Rockwell methods, and overcomes their basic shortcomings. However, it is not as simple as the Rockwell method, and the Vickers method is rarely used in the steel pipe standard.
For annealed stainless steel weld tubes with an inner diameter above 6.0mm and a wall thickness below 13mm, W-B75 Vickers hardness tester can be used, which is very fast and easy to test and suitable for fast non-destructive qualification inspection of stainless steel weld tubes. For stainless steel weld tubes with an inner diameter greater than 30mm and a wall thickness greater than 1.2mm, Rockwell hardness tester is used to test HRB and HRC hardness. For stainless steel weld tubes with an inner diameter greater than 30mm and a wall thickness less than 1.2mm, a surface Rockwell hardness tester is used to test HRT or HRN hardness. For stainless steel weld tubes with an inner diameter less than 0mm and greater than 4.8mm, a dedicated Rockwell hardness tester for pipes is used to test HR15T hardness. When the inner diameter of the stainless steel weld tube is greater than 26mm, Rockwell or surface Rockwell hardness tester can also be used to test the hardness of the inner wall of the pipe.