Hardness is one of the most commonly used indexes to evaluate the mechanical properties of metal materials. The essence of hardness is the ability of a material to resist pressure from another harder material. For the tested material, the hardness represents the comprehensive performance of multiple physical quantities such as elasticity, plasticity, strength, toughness and wear resistance reflected under a certain indenter and test force. Because the hardness test can reflect the performance difference of metal materials under different chemical composition, structure and heat treatment process conditions, the hardness test is widely used in the inspection of metal properties, supervising the quality of heat treatment process and the development of new materials.
There are two main types of test methods for metal hardness testing. One is the static test method, in which the application of test force is slow and without impact. The determination of hardness is mainly determined by the depth of the indentation, the projected area of the indentation or the size of the indentation area. Static test methods include Brinell, Rockwell, Vickers, Knoop, Webster, Pap and so on. Among them, Brinell, Rockwell, and Vickers test methods are the most widely used, and they are the main test methods for metal hardness testing. The Rockwell hardness test here is the most widely used. It is widely used for product inspection. According to statistics, 70% of the hardness testers currently in use are Rockwell hardness testers. Another type of test method is the dynamic test method, in which the application of test force is dynamic and impactful. This includes Shore and Leeb hardness test methods. The dynamic test method is mainly used for hardness testing of large, immovable workpieces.
Welded pipes can choose three hardness test methods, Brinell, Rockwell and Vickers, to determine the HB, HRB (or HRC) and HV hardness values. Only one of the three hardness values can be measured.
The following briefly introduces the application of several welded pipes :
1. Usually welded pipes are used for the transportation of usually lower pressure fluids such as water, gas, air, oil and heating steam.
2. Generally, carbon steel wire casing (GB3640-88) is a steel pipe used to maintain wires in electrical installations such as industrial and civil buildings, installations and equipment.
3. Straight seam electric welded pipe (YB242-63) is a steel pipe whose weld seam is parallel to the longitudinal direction of the steel pipe. Usually divided into metric electric welded pipe, electric welded thin-walled pipe, transformer cooling oil pipe and so on.
4. Spiral seam submerged arc welded pipe (SY5036-83) for pressure-bearing fluid transportation is made of hot-rolled steel strip coils, which are spirally formed at regular temperature and welded by double-sided submerged arc welding. The spiral is used for pressure-bearing fluid transportation. Seam the steel pipe. The steel pipe has strong pressure bearing capacity, good welding performance and safe and reliable operation. The steel pipe has a large diameter, high transportation efficiency, and can save investment in laying pipelines. Mainly used to transport oil and natural gas pipelines.
5. Spiral seam high-frequency welded pipes (SY5038-83) for conveying pressure fluids are made of hot-rolled steel strip coils, which are spirally formed at regular temperatures, and are joined by high-frequency lap welding. They are used for conveying pressure fluids. Spiral seam high frequency welded steel pipe. The steel pipe has strong pressure-bearing capacity and good plasticity, which is convenient for welding and processing. It is safe and reliable to use, with large diameter of the steel pipe, high transportation efficiency, and can save the investment of laying pipelines through various strict and scientific inspections and tests. It is mainly used to lay pipelines for transporting oil and natural gas.
6. Spiral seam submerged arc welded steel pipe (SY5037-83) for conveying low-pressure fluids is usually made of hot-rolled steel strip coils, which are spirally formed at regular temperatures, and are made of double-sided active submerged arc welding or single-sided welding. Submerged arc welded steel pipes for the transportation of low-pressure fluids such as water, gas, air, and steam.
Tips: Straight seam steel pipe is a steel pipe whose weld seam is parallel to the longitudinal direction of the steel pipe. Straight seam steel pipes can be divided into high-frequency straight seam steel pipes (ERW Pipe) and submerged arc welded straight seam steel pipes (LSAW Pipe) according to the production process. Straight seam welded pipe has simple production process, high production efficiency, low cost and rapid development.
ASTM A53 Grade B is the material under the American steel pipe standard, API 5L Gr.B is also the American standard material, A53 GR.B ERW refers to the electric resistance welded steel pipe of A53 GR.B; API 5L GR.B Welded refers to the material Welded steel pipe of API 5L GR.B.