In general, hardness indicators of Brinell, Rockwell and Vickers hardness index are adopted to measure the hardness of steel.

1. Brinell Hardness

In stainless steel tube standard, Brinell Hardness is the most commonly used, often impress diameter is applied to express the hardness of the material, which is intuitive and convenient. However, it is not applicable to harder or thinner steel pipes.

2. Rockwell Hardness

Stainless steel Rockwell Hardness test is the same as Brinell Hardness test, applying indentation test method. But the difference is that the former test the depth of indentation. Rockwell Hardness test method is applied widely at present, among which application of HRC in steel tube standard is only after Brinell Hardness. Rockwell Hardness can be applied to test extremely soft and extremely hard metal materials, making up for the inadequacy of Brinell method, and it is simpler, hardness value can be read directly from the dial of the hardness machine. But because of its small creasing, so, the hardness value is not as accurate as Brinell Hardness.

3. Vickers Hardness

Stainless steel pipe Vickers Hardness indentation test is also one of the ways that can be used for the determination of thin metal materials and surface hardness. It has the main advantages of the Brinell and Rockwell methods, and overcomes their basic drawbacks, but not as simple as Rockwell method, Vickers method is seldom applied in the steel tube standard.