The hardness test is to slowly press a hard indenter into the surface of the sample under specified conditions, and then test the depth or size of the indentation to determine the hardness of the material. Hardness test is the simplest, fastest and easiest to implement method in material mechanical property testing. The hardness test is non-destructive, and there is an approximate conversion relationship between the material hardness value and the tensile strength value.
Since the tensile test is inconvenient to test and it is convenient to convert hardness to strength, more and more people only test the hardness of materials and less often test their strength. Especially due to the continuous advancement and innovation of hardness tester manufacturing technology, it is now possible to directly test the hardness of some materials that were previously unable to be directly tested, such as stainless steel pipes, stainless steel wires, extremely thin stainless steel plates, and stainless steel strips. . Therefore, there is a trend that hardness testing gradually replaces tensile testing.
In stainless steel standards, three hardness test methods, including Bu, Luo and Wei, are generally stipulated to measure, (or) and hardness values. It is stipulated that only one of the three hardness values can be measured.
The testing method for the hardness of stainless steel has a prominent feature in the American metal material standards regarding the hardness test, which is that Rockwell hardness test is given priority, supplemented by Brinell hardness test, and rarely Using Vickers hardness test, the United States believes that Vickers hardness test should be mainly used for metal research and testing of thin and small parts.
Both Chinese and Japanese standards use three hardness tests at the same time. Users can choose one of them to test stainless steel materials according to the thickness and state of the material and their own conditions. The provisions on tensile test and hardness test in the Japanese stainless steel standards are the same as the corresponding Chinese standard tables, and the values are similar. Here you can see traces of the Chinese standards adopting Japanese standards with reference to them.
In terms of stainless steel hardness testing, the Rockwell hardness tester is an instrument worthy of priority. It is simple and easy to operate. It can directly read the hardness value without the need for a professional inspector. It has high testing efficiency and is very suitable for factory use.
Regarding the use of Rockwell hardness tester to test the hardness of stainless steel, there are generally only two scales stipulated in stainless steel standards: and and . For annealed stainless steel materials, the hardness value corresponding to each grade of stainless steel generally stipulates that the hardness value should not be greater than a certain value, generally within a range. For quenched and tempered martensitic stainless steel, it generally corresponds to each grade of stainless steel, and the hardness value is not less than a certain value, generally within a range.
The stainless steel standard only stipulates the use of Rockwell hardness tester and scale. In fact, the surface Rockwell hardness tester can also be used to test stainless steel. Because its principle is exactly the same as the Rockwell hardness tester, but the test force is smaller. And its hardness value can be easily converted into Brinell hardness or Vickers hardness. The corresponding conversion tables can be found on the company's website. These conversion tables are derived from American standards or international standards
. For thin-walled stainless steel pipes, thin stainless steel plates, thin stainless steel strips, thin stainless steel wires, etc., it is very convenient to use a surface Rockwell hardness tester. 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 thin stainless steel plates, stainless steel strips and thin stainless steel pipes, making it difficult to solve domestic problems in the past. The problem is easily solved.
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