Hardness of cs seamless pipe

Cs seamless pipe to be tested for mechanical properties. Cs seamless steel pipes are widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile drive shafts, bicycle frames, and steel scaffolds used in building construction, etc. Steel pipes are used to make ring parts. It can improve the utilization rate of materials, simplify the manufacturing process, save materials and processing man-hours, and has been widely used in steel pipes. There are two main types of mechanical property testing methods, one is tensile test and the other is hardness test. The next thing we will introduce is the hardness test of cs seamless pipe, that is, the ability of metal materials to resist the depression of hard objects on the surface, which is called hardness.

Metrics

1. Brinell hardness

In CS seamless steel pipe standards, Brinell hardness is widely used, and the hardness of the material is often expressed by the indentation diameter, which is intuitive and convenient. But it is not suitable for steel pipes of harder or thinner steel.

2. Rockwell hardness

The Rockwell hardness test of cs seamless 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 at present, among which HRC is second only to Brinell hardness HB in steel pipe standards. Rockwell hardness is suitable for measuring metal materials ranging from extremely soft to extremely hard. It makes up for the shortcomings of the Brinell method. It is simpler than the Brinell method and can directly read the hardness value from the dial of the hardness machine. However, due to its small indentation, the hardness value is not as accurate as the Brinell method.

3. Vickers hardness

The cs seamless steel tube Vickers hardness test is also an indentation test method that can be used to determine the hardness of very thin metal materials and surface layers. It has the main advantages of the Brinell and Rockwell methods, and overcomes their basic shortcomings, but it is not as simple as the Rockwell method, and the Vickers method is rarely used in steel pipe standards.

Detection method

The tensile test is to make a sample of cs seamless steel pipe, pull the sample to fracture on a tensile testing machine, and then measure one or several mechanical properties. Usually only tensile strength, yield strength, elongation after fracture and reduction of area are measured. Tensile test is the most basic test method for mechanical properties of metal materials. Almost all metal materials have specified tensile tests as long as they have requirements for mechanical properties. Especially for those materials whose shapes are not convenient for hardness testing, tensile testing has become the only means of testing mechanical properties.

The hardness test is to slowly press a hard indenter into the surface of the sample with a hardness gauge according to the 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 method in material mechanical performance test. 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 the tensile strength value, which has great practical significance.

Since the tensile test is not convenient for testing, and it is very convenient to convert from hardness to strength, more and more people only test the hardness of materials and seldom test their strength. Especially due to the continuous improvement and innovation of hardness tester manufacturing technology, some materials that could not directly test the hardness before, such as seamless steel pipes, stainless steel plates and stainless steel strips, etc., are now possible to directly test the hardness. Therefore, there is a tendency that the hardness test gradually replaces the tensile test.

Detection Tool

For the annealed steel pipe dimension with an inner diameter of 6.0mm or more and a wall thickness of 13mm or less, a W-B type Webster hardness tester can be used. It is very fast and easy to test, and is suitable for fast and non-destructive qualification inspection of cs seamless steel pipes. For cs seamless steel pipes with an inner diameter greater than 30mm and a wall thickness greater than 1.2mm, use a Rockwell hardness tester to test the hardness of HRB and HRC. For cs seamless steel pipes with an inner diameter greater than 30mm and a wall thickness less than 1.2mm, the surface Rockwell hardness tester is used to test the hardness of HRT or HRN. For cs seamless steel pipes with an inner diameter less than 0mm and greater than 4.8mm, use a special Rockwell hardness tester for pipes to test the hardness of HR15T. When the inner diameter of the cs seamless steel pipe is greater than 26mm, the hardness of the inner wall of the pipe can also be tested with a Rockwell or superficial Rockwell hardness tester.

Article source: https://article-realm.com/article/Finance/36311-Hardness-of-cs-seamless-pipe.html