In general, seamless steel pipe uses Brinell, Rockwell, Vickers three hardness indicators to measure the hardness.
1. Brinell hardness test
In the standard of seamless steel pipe, Brinell hardness is used most, it often use indentation diameter to represent the hardness of the material, which is both intuitive and convenient. But it is not suitable for harder or thinner steel pipes.
2. Rockwell hardness test
The Rockwell hardness test of seamless steel tubes is the same as the Brinell hardness test, they are both indentation test method. The difference is that Rockwell hardness measures the depth of indentation. Rockwell hardness test is a widely-used method currently, HRC is next only to after Brinell hardness HB in the steel pipe standard. Rockwell hardness can be applied to measure metal material from very soft to very hard, which makes up for the weakness of Brinell method. And it is simpler than the Brinell method, it can read out the hardness value directly from the hardness of the dial. However, its hardness value is not as good as the Brinell method because its indentation is small.
3. Vickers hardness test
Vickers hardness test of seamless steel tube is also an indentation test method, it can be used to measure the thin metal materials and surface layer hardness. It has the main advantages of the Brinell and Rockwell methods, and overcomes their basic shortcomings. But it is not as easy as the Rockwell method, so Vickers method is rarely used in the steel pipe standard.
