The hardness of stainless steel pipe is roughly divided into three types: Brinell, Rockwell and Vickers hardness. Basically, most stainless steel pipe manufacturers classify stainless steel pipes according to these three hardness methods.
1. Brinell hardness
In the specification of stainless steel pipes, Brinell hardness is widely used, and the indentation diameter is often used to indicate the hardness of the material, which is both intuitive and convenient. However, it is not suitable for steel pipes of harder or thinner steel.
2. Rockwell hardness
The Rockwell hardness test of stainless steel pipe 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. Rockwell hardness test is a widely used method, during which HRC is second only to Brinell hardness HB in steel pipe specifications. Rockwell hardness can be used to measure metal materials ranging from extremely soft to extremely hard. It makes up for the difference of the Brinell method. It is simpler than the Brinell method. The hardness value can be read directly from the dial of the hardness machine. However, because of its small indentation, the hardness value is not as good as the Brinell method.
3. Vickers hardness
The stainless steel tube Vickers hardness test is also an indentation test method, which can be used to determine the hardness of very thin metal materials and the outer surface layer. It has the primary advantages of Brinell and Rockwell method, and overcomes their fundamental defects, but it is not as concise as Rockwell method. Vickers method is rarely used in steel pipe specifications.
Stainless steel pipe hardness testing method The hardness testing of stainless steel should take into account its mechanical function, which is related to the function and quality of deformation, stamping, cutting and other processing using stainless steel as raw material. Therefore, all stainless steel pipes must be tested for mechanical function.
The mechanics function test methods are mainly divided into two categories, one is the tensile test, and the other is the hardness test.
The tensile test is to make a stainless steel tube into a sample, pull the sample to crack on a tensile testing machine, and then measure one or several mechanical functions. Generally, only the tensile strength, yield strength, elongation after fracture and section shrinkage are measured. Rate. The tensile test of stainless steel pipe manufacturers is the fundamental mechanical function test method of metal materials. All metal materials are used, as long as the mechanical function is required, the tensile test is regulated. Especially for those materials whose shape is not convenient for hardness test, tensile test has become a mechanical function testing method.
The hardness test is to slowly press a hard indenter into the surface of the sample according to regular conditions, and then test the depth or size of the indentation to determine the hardness of the material. Hardness experiment is a simple, agile and easy to implement method in material mechanics function experiment. If the hardness test is right or wrong and destructive, there is an approximate conversion relationship between the hardness value of the data and the tensile strength value. The hardness value of the data can be converted into the tensile strength value, which has great useful meaning.
Because the tensile test is not easy to test, and it is convenient to convert the hardness to the strength, more and more people only test the hardness of the data and less test the strength. Especially because of the continuous progress and innovation of hardness tester manufacturing technology, some materials that could not be directly tested before, such as stainless steel tubes, stainless steel plates and stainless steel strips, are now possible to directly test the hardness.
