Organic substances (such as melons and vegetables, noodle soup, phlegm, etc.) adhered to the surface of stainless steel constitute organic acids in the presence of water and oxygen. For a long time, the corrosion of organic acids on the metal surface.
The welding performance is also much better than that of ferritic stainless steel. Generally, preheating is not required before welding and heat treatment is not required after welding.
.Standard classification 4-1 classification: national standard GB industry standard Yb local standard enterprise standard qcb4-2 classification: product standard packaging standard basic standard 4-3 standard level (divided into three levels): y level: international advanced level I level: international general level H level: domestic advanced level 4-4 national standard: stainless steel bar (level I) gb4241-84 stainless welding disc Park (level H)
. 309— It has better temperature resistance.
In view of the external export difficulties,Ocr25Ni20 stainless steel plate, on the one hand China's stainless steel industry needs to improve, but it is important for China's stainless steel industry to continuously improve its quality level and comprehensively upgrade.
Stainless steel pipe will not rust, it will be corroded and oxidized slowly, but it will take a long time. In general, stainless steel pipes will not rust. However if the stainless steel pipe is used or maintained improperly, or the environment in which the stainless steel pipe is located is too bad, the stainless steel pipe may rust. When we see rust spots on the steel surface, we can quickly confirm that it is a sign of rust. Why does stainless steel pipe rust? First of all let's understand the structure of stainless steel pipe: stainless steel pipe is a crystal solid composed of atoms similar to a piece of toys. In addition to iron, it also contains its metal components,Stainless steel plate drilling bit, such as chromium, nickel, titanium, etc. Chromium and nickel have anti rust function. It forms a protective film - passive film to prevent stainless steel pipe from rusting. Generally as long as the film is not damaged, broken or contaminated by impurities, the stainless steel pipe will not rust. However, if the blunt film is damaged due to improper use or maintenance, the stainless steel pipe will rust.
408— Good heat resistance, weak corrosion resistance, 11% Cr, 8% Ni.
Rockwell hardness the Rockwell hardness test of stainless steel pipe is the same as Brinell hardness test. The difference is that it measures the depth of indentation. Rockwell hardness test is widely used at present, and HRC is second only to Brinell hardness Hb in steel pipe standards. Rockwell hardness can be used to measure metal materials from very soft to very hard, which makes up for the disadvantage of Brinell method, due to its small indentation, the hardness value is not as accurate as Brinell method.
The steady creep rate is usually used to evaluate the long-time creep performance of materials. For the application of long-life materials, the steady-state creep rate of stainless steel pipe under high temperature and stress is the key index of the material, and can be extrapolated. The following are the test results of stainless steel pipe under different test conditions. The results show that the steady-state creep rate of stainless steel pipe sample is in the order of magnitude after creep at 550 ℃ (90mpa600 ℃ (85mpa) for 500h; when the temperature condition increases to 650 ℃ (the stress decreases to 70MPa), the creep performance of stainless steel pipe sample is good, and the steady-state creep rate is in the order of magnitude; when the temperature further increases to 700 ℃ (the temperature creep rate of 65mpa stainless steel pipe sample increased to 800 ℃ (65mpa steady-state creep rate reaches the maximum value under several test conditions, and creep fracture occurs. See for the change of steady-state creep rate of stainless steel pipe sample under several conditions. When the temperature increases, the material maintains a low level of creep rate. Under 650 ℃ 70MPa, s creep deformation rate does not increase, which shows little influence on the temperature and stress, and creep fracture occurs under this condition Compared with several other common structural materials, it can be seen that the creep performance of several materials is better than that of ordinary materials under all test conditions. After 500 hours of test, the total strain does not exceed 0.12%. The curve is relatively stable and the fluctuation is small, indicating that the test data is stable and reliable. Stainless steel pipes are widely used because of their excellent corrosion resistance It is widely used in petrochemical industry, pipeline transportation and other working conditions with strong corrosive media. The main reason for the corrosion resistance of stainless steel pipes is the addition of a large number of elements CrNi, and Cr is the main element determining the corrosion resistance of stainless steel pipes. The electrode potential of stainless steel pipes jumps with the increase of Cr content. However, stainless steel pipes are in the subsequent heat treatment During the treatment Cr element will precipitate into the matrix in the form of carbide. On the one hand, the hardness of Cr carbide is larger than that of the matrix, and the service wear process can improve the wear resistance of stainless steel pipe. On the other hand, the precipitation of Cr containing carbide will lead to Cr Element dilution zone in some parts of the matrix, increase the number of batteries of the material, reduce the electrode potential of stainless steel pipe and reverse the corrosion Therefore, in order to obtain good corrosion and wear resistance, the combination of mechanical properties and corrosion resistance of stainless steel pipe materials needs to be considered. At present, some scholars have studied the effects of austenitizing temperature and time, tempering temperature and time on the mechanical properties of stainless steel pipe by heat treatment to change the corrosion resistance of stainless steel pipe And corrosion resistance, it is found that austenitizing temperature can change mechanical properties, but has little effect on corrosion performance, while tempering temperature has a great effect on the corrosion resistance of materials. Appropriate austenitizing temperature and tempering temperature can improve the corrosion and wear resistance of materials. Some scholars use surface treatment to improve the corrosion and wear resistance of materials, It is concluded that low-temperature nitriding forms a diffusion layer on the surface of the material, improves the wear resistance of the material, interacts with Cr and chemically stable phase 07-fe3n to improve the corrosion resistance of the material.
ranking.Organic substances (such as melons and vegetables, noodle soup, phlegm, etc.) adhered to the surface of stainless steel constitute organic acids in the presence of water and oxygen. For a long time, the corrosion of organic acids on the metal surface.
[(outer diameter wall thickness) wall thickness] 0.02491 = kg m (weight per meter)
The inventory of stainless steel pipes may be an important factor in market conditions. This is because at this stage, steel inventory has become an important index to investigate and judge the situation of stainless steel pipeline shopping malls, and has become a wind vane to judge the future market trend. What was the stock of stainless steel tubes at that time? It directly affects the air of shopping malls, and then distributes the business behavior of participants in shopping malls
From the perspective of metallography, because stainless steel contains chromium, a very thin chromium film is formed on the surface, which is separated from the corrosion resistance of oxygen invaded in the steel.
install.In order to prevent the occurrence of welding pores, oil stain, etc.
This material without titanium and niobium has an inherent tendency of intergranular corrosion. Intergranular corrosion can be reduced by adding titanium and niobium and stabilizing treatment. It is a kind of high alloy steel that can corrode in air or chemical corrosive medium. Stainless steel has beautiful surface and good corrosion resistance. It does not have to undergo surface treatment such as color plating to play a role of rust free
Chinese brand cold rolled non oriented silicon steel strip (sheet) means: DW + 100 times of iron loss value (at the frequency of 50Hz, the magnetic induction peak with sinusoidal waveform is the unit weight iron loss value of 5t) + 100 times of thickness value. For example,Stainless steel spring band, dw470-50 represents cold-rolled non oriented silicon steel with iron loss value of 7W / kg and thickness of 0.5mm. Now the new model is 50W470.
.The pipes for pipe cutting shall be professionally cut by stainless steel. Rotate it for two circles, then slightly tighten the piece, and then rotate it for two circles until it is cut off. It must not be enough to allow personal strength to be in place at one time to lock the piece to cut off the pipe, otherwise the pipe end will be cut off, and the pipe fittings or rubber rings cannot be inserted; After the pipe above DN65 is cut, the internal and external burrs must be removed with a hand grinder, and an appropriate outer slope opening shall be opened at the same time to avoid damaging the sealing ring.
408— Good heat resistance, 11% Cr, 8% Ni.
409— Cheap model (British and American), usually used as automobile exhaust pipe