焊管是用钢板或钢带经过弯曲成型，然后经焊接制成。按焊缝形式分为直缝焊管和螺旋焊管。按用途又分为一般焊管、镀锌焊管、吹氧焊管、电线套管、公制焊管、托辊管、深井泵管、汽车用管、变压器管、电焊薄壁管、电焊异型管和螺旋焊管。 一般焊管:一般焊管用来输送低压流体。用Q195A、Q215A、Q235A钢制造 。也可采用易于焊接的其它软钢制造。钢管要进行水压、弯曲、压扁等实验，对表面质量有一定要求，通常交货长度为4-10m，常要求定尺(或倍尺)交货。焊管的规格用公称口径表示(毫米或英寸)公称口径与实际不同，焊管按规定壁厚有普通钢管和加厚钢管两种，钢管按管端形式又分带螺纹和不带螺纹两种。
Record: 1. Hardness Testing Method of Seamless Steel Pipe 2. Hardness Testing Method of Welded Pipe 3. Hardness Testing Method of Tin Matte
4. Testing methods for die hardness and die steel hardness 5. On-site testing methods for strip steel hardness 6. Testing methods for hardness of heat-treated workpieces
7. Testing methods for hardness of aluminium profiles 8. Testing methods for hardness of castings 9. Testing methods for hardness of stainless steel strips 10. Testing methods for hardness of stainless steel plates 1. Testing methods for hardness of seamless steel tubes
1. Hardness Index of Seamless Steel Pipe
The hardness of seamless steel pipe is generally measured by three hardness indexes, Brinell, Rockwell and Vickers.
1) Brinell hardness is the most widely used standard for seamless steel pipe. It is often expressed by indentation diameter, which is both intuitive and convenient. But it is not suitable for steel pipes with harder or thinner steel.
2) Rockwell hardness test of seamless steel pipe with Rockwell hardness is the same as Brinell hardness test, which is indentation test method. The difference is that it measures the depth of indentation. Rockwell hardness test is a widely used method at present. HRC is second only to Brinell hardness HB in steel pipe standard. Rockwell hardness can be applied to the determination of metal materials from very soft to very hard. It makes up for the shortcomings of the Brinell method. It is simpler than the Brinell method and can read the hardness value directly from the dial of the hardness machine. However, because of its small indentation, the hardness value is not as accurate as that of Brinell method.
3) Vickers hardness test of seamless steel pipe with Vickers hardness is also an indentation test method, which can be used to measure the hardness of very thin metal materials and surface layer. It has the main advantages of Brinell's method and Rockwell's method, and overcomes their basic shortcomings, but it is not as simple as Rockwell's method, and Vickers method is seldom used in steel pipe standards.
2. Hardness Testing Method of Seamless Steel Tube
Hardness testing of stainless steel should consider its mechanical properties, which is related to the properties and quality of deformation, stamping and cutting of stainless steel as raw materials. Therefore, all seamless steel tubes should be tested for mechanical properties. There are two kinds of testing methods for mechanical properties, one is tensile test and the other is hardness test.
Tensile test is to make seamless steel tubes into specimens. The specimens are pulled to fracture on a tensile testing machine, and then one or several mechanical properties are measured. Usually, only tensile strength, yield strength, elongation after breaking and section shrinkage are measured. Tensile test is the most basic test method of mechanical properties of metal materials. Almost all metal materials, as long as the mechanical properties are required, have stipulated the tensile test. Especially for those materials whose shape is not easy to carry out hardness test, tensile test has become a means of Weiyi's mechanical properties testing.
Hardness test is to determine the hardness of the material by slowly pressing a hard indenter into the surface of the sample under specified conditions and then testing the indentation depth or size. Hardness test is the simplest, quickest and easiest method in material mechanical property test. Hardness test is non-destructive, and there is an approximate conversion relationship between hardness and tensile strength. The hardness value of the material can be converted into the tensile strength value, which has great practical significance.
Due to the inconvenience of tensile test and the convenience of conversion from hardness to strength, more and more people only test the hardness of materials and less test their strength. Especially due to the continuous progress and innovation of hardness tester manufacturing technology, some materials which could not directly test hardness, such as seamless steel pipe, stainless steel plate and stainless steel strip, are now possible to directly test hardness. Therefore, there is a tendency that the hardness test will gradually replace the tensile test.
Tensile test and hardness test are stipulated in most national standards for stainless steel. For materials that are not easy to carry out hardness tests, such as seamless steel tubes, only tensile tests are required. In the standard of stainless steel, three hardness test methods of cloth, lol and vitamin D are generally stipulated. The hardness values of HB, HRB (or HRC) and HV are determined. It is stipulated that only one of the three hardness values can be measured. In particular, the company's new portable surface Rockwell hardness tester, pipe Rockwell hardness tester, can be thin to 0.05mm stainless steel plate, stainless steel strip and fine to 4.8mm seamless steel tube for rapid and accurate hardness testing, making the past difficult problems in China to solve.
3. Hardness Testing Tool for Seamless Steel Pipe
W-B75 type Wechsler hardness tester can be used for annealed seamless steel pipe whose inner diameter is more than 6.0 mm and wall thickness is less than 13 mm. This tester is very fast and simple, and is suitable for rapid and non-destructive inspection of seamless steel pipe. Seamless steel tubes with inner diameter greater than 30 mm and wall thickness greater than 1.2 mm are tested by Rockwell hardness tester for HRB and HRC hardness. Seamless steel tubes with inner diameter greater than 30 mm and wall thickness less than 1.2 mm are tested by surface Rockwell hardness tester for HRT or HRN hardness. Seamless steel pipe with inner diameter less than 0 mm and larger than 4.8 mm is tested by Rockwell hardness tester. When the inner diameter of seamless steel tube is larger than 26 mm, Rockwell hardness tester or surface Rockwell hardness tester can also be used to test the hardness of the inner wall of the tube.
Hardness Testing of Welded Pipe
Welded pipe is made of steel plate or strip after bending and welding. According to the weld form, it can be divided into straight welded pipe and spiral welded pipe. According to its use, it can be divided into general welded pipe, galvanized welded pipe, oxygen-blowing welded pipe, wire sleeve, metric welded pipe, idler pipe, deep well pump pipe, automobile pipe, transformer pipe, welded thin-walled pipe, welded special-shaped pipe and spiral welded pipe. General welded pipe: General welded pipe is used to transport low-pressure fluid. Using Q195A and Q2