Hardness Testing Method For Seamless Steel Pipe
- Jun 03, 2018 -

The hardness test of stainless steel should take into account its mechanical properties, which is related to the performance and quality of processing such as deformation, stamping, and cutting performed with stainless steel as raw material. Therefore, all the seamless steel tubes are tested for mechanical properties. What is the hardness test method for seamless steel tubes? There are two types of mechanical properties test methods. One is tensile test, and the other is hardness test.

Tensile test is made of seamless steel pipe into a sample, in the tensile tester to pull the sample to fracture, and then determine one or several mechanical properties, usually only measured tensile strength, yield strength, elongation after fracture and rate of reduction in area. Tensile test is the most basic test method for mechanical properties of metal materials. Almost all metal materials, as long as the mechanical properties are required, have specified tensile tests. Especially for those materials whose shape is not convenient for hardness testing, the tensile test becomes the only means of testing the mechanical properties.

The hardness test is to determine the hardness of a material by slowly pressing a hard indenter with a durometer under specified conditions onto the surface of the specimen and then measuring the indentation depth or dimension. Hardness testing is the simplest, fastest, and easiest to implement method for testing the mechanical properties of materials. The hardness test is non-destructive and there is an approximate conversion between the material hardness value and the tensile strength value. The hardness value of the material can be converted into the tensile strength value, which has great practical significance.

Since the tensile test is inconvenient for testing and is easily converted from hardness to strength, more and more people only test the hardness of the material and test its strength less. 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 pipes, stainless steel plates, and stainless steel bands, are now possible to directly test the hardness. Therefore, there is a tendency for hardness tests to gradually replace tensile tests.

Most of the national standards for stainless steel materials specify both tensile tests and hardness tests. For 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 are generally specified, namely, HB, HRB (or HRC) and HV hardness values. It is stipulated that only one of the three hardness values can be measured. In particular, the latest portable surface Rockwell hardness tester and tube Rockwell hardness tester can perform fast and accurate hardness testing on stainless steel plates as thin as 0.05mm, stainless steel bands, and seamless steel pipes as fine as 4.8mm. Problems that are difficult to solve at home have been solved.