Generally, the hardness of seamless steel pipes has three standards: Brinell Hardness, Rockwell Hardness and Vickers Hardness.
1. Brinell Hardness
Brinell Hardness is the most common standard for seamless steel pipes, generally use diameter of indentation to represent the hardness of material, which is intuitive and simple. However, the standard is not suitable for hard and thin steel pipes.
Rockwell Hardness is also use indentation to represent the hardness, but Rockwell measures its depth rather than diameter. Rockwell Hardness is widely applied in testing hardness of seamless steel pipes, the standard HRC is the most popular testing method next to Brinell Hardness (HB). Rockwell Hardness can be used to test both extremely soft and hard material which supplements shortcomings of Brinell Hardness. The number of hardness can be read directly from the dial. However, due to slighter indentation, Rockwell Hardness is less accurate than Brinell Hardness.
3. Vickers Hardness
Vickers Hardness is also depending on testing indentation which can be applied to test thin metal material. Vickers Hardness combines advantages of Brinell and Rockwell, but the measurement is not as convenient as Rockwell, therefore is not widely used as the hardness standard.