Seamless steel tube hardness testing method
The hardness test of stainless steel should take into account its mechanical properties, which is related to the performance and quality of deformation, stamping, cutting and other processing using stainless steel as a raw material. Therefore, all seamless steel tubes must be tested for mechanical properties. The mechanical property test methods are mainly divided into two categories, one is tensile test and the other is hardness test.
The tensile test is to make a seamless steel tube into a sample, pull the sample to break on a tensile test machine, and then measure one or several mechanical properties, usually only the tensile strength, yield strength, elongation after break and rate of reduction in area. Tensile test is the most basic mechanical property test method for metal materials. Almost all metal materials, as long as there are requirements for mechanical properties, all provide tensile tests. Especially for materials whose shape is not convenient for hardness testing, tensile testing becomes the only means of testing mechanical properties.
The hardness test is to slowly press a hard indenter into the surface of the sample according to the specified conditions, and then test the depth or size of the indentation to determine the hardness of the material. The hardness test is the simplest, fastest and easiest method to perform in the mechanical properties test of materials. The hardness test is non-destructive, and there is an approximate conversion relationship between the material hardness value and the tensile strength value. The hardness value of the material can be converted into a tensile strength value, which has great practical significance.
Because the tensile test is not easy to test, and it is very convenient to convert from hardness to strength, people are increasingly testing only the hardness of the material and less testing its strength. In particular, due to the continuous advancement and innovation of the hardness tester manufacturing technology, some materials that could not be directly tested for hardness, such as seamless steel tubes, stainless steel plates and stainless steel bands, are now possible to directly test the hardness. Therefore, there is a tendency that the hardness test gradually replaces the tensile test.
Most of the national standards for stainless steel materials specify both tensile test and hardness test. For those materials that are not convenient for hardness testing, such as seamless steel tubes, only tensile tests are specified. In the stainless steel standard, three hardness test methods of cloth, Luo, and Wei are generally specified to determine the hardness values ​​of HB, HRB (or HRC), and HV, and only one of the three hardness values ​​is required. In particular, the company's newly developed portable surface Rockwell hardness tester and pipe Rockwell hardness tester can quickly and accurately test the hardness of stainless steel plates as thin as 0.05mm, stainless steel strips and seamless steel tubes as thin as 4.8mm, making Problems that were difficult to solve in the past have been solved.
Seamless steel tube hardness testing tool
Seamless steel tubes with an inner diameter of 6.0mm or more and a wall thickness of 13mm or less can be annealed seamless steel tubes. The W-B75 Vickers hardness tester can be used. It is very fast and simple to test, suitable for rapid and non-destructive testing Conformity inspection. Seamless steel pipes with inner diameter greater than 30mm and wall thickness greater than 1.2mm are tested with Rockwell hardness tester for HRB and HRC hardness. Seamless steel tubes with inner diameter greater than 30mm and wall thickness less than 1.2mm are tested with surface Rockwell hardness tester to test HRT or HRN hardness. For seamless steel pipes with an inner diameter of less than 0mm and greater than 4.8mm, a special Rockwell hardness tester for pipes is used to test the HR15T hardness. When the inner diameter of the seamless steel pipe is greater than 26mm, you can also use the Rockwell or surface Rockwell hardness tester to test the hardness of the inner wall of the pipe.
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