Test methods for mechanical properties of carbon seamless steel tubes

The mechanical properties test methods are mainly divided into two categories: tensile test and hardness test. The tensile test is to make a sample of carbon steel tube, break the sample on a tensile testing machine, and then measure one or several mechanical properties, usually tensile strength, yield strength, elongation after fracture and area shrinkage. 

Tensile test is the basic mechanical property test method of metal materials. Tensile tests are required for almost all metal pipes as long as mechanical properties are required. Especially for hardness testing of materials that are not easy to form, tensile testing is the only means of testing mechanical properties.

The hardness test is to slowly press a hard indenter into the surface of the carbon seamless steel tube under specified conditions, and then use the depth or size of the test indentation to determine the hardness of the material. Hardness test is a simple, fast and easy-to-implement method in material mechanical property test. The hardness test is non-destructive, and there is an approximate conversion relationship between the material hardness value and the tensile strength value. That is to say, the hardness value of the steel pipe can be converted into the tensile strength value, which has great practical significance.

Because the tensile test is not easy to test, and it is also easy to convert hardness into strength. As a result, more and more people are only testing the hardness of materials and rarely their strength. It is now possible to directly test the hardness of some materials that could not be directly tested before, such as seamless steel tubes, stainless steel tubes, stainless steel plates and stainless steel strips, thanks to the continuous advancement and innovation of hardness tester manufacturing technology.

Therefore, the hardness test has a tendency to gradually replace the tensile test. Most stainless steel welded tube standards specify tensile and hardness tests. For materials that are inconvenient for hardness testing, such as stainless steel seamless tubes, only tensile testing is required. In the Chinese and Japanese standards, three hardness test methods of Brinell, Rockwell and Vickers are generally prescribed to determine the hardness value of stainless steel seamless tubes. Hardness test. For the hardness test of stainless steel, the Rockwell hardness tester is the preferred instrument. Its equipment is simple and easy to operate, and the hardness value can be directly read without professional testing personnel. The efficiency of the test is high and it is very suitable for factory use.