When brown rust spots (spots) appear on the surface of stainless steel pipes, people are amazed: “Stainless steel does not rust, and if it rusts, it is not stainless steel, and there may be a problem with the steel.” In fact, this is a one-sided misconception about the lack of understanding of stainless steel. Stainless steel will also rust under certain conditions! Stainless steel has the ability to resist atmospheric oxidation—that is, rust resistance, and also has the ability to corrode in media containing acids, alkalis, and salts—that is, corrosion resistance. However, the size of its anti-corrosion ability varies with the chemical composition of its steel itself, the state of mutual addition, the conditions of use and the type of environmental media. For example, 304 steel pipe has excellent corrosion resistance in a dry and clean atmosphere, but if it is moved to a coastal area, it will rust soon in the sea fog containing a lot of salt; and 316 steel pipe is good performance. Therefore, it is not any kind of stainless steel that can resist corrosion and rust in any environment. Stainless steel is a very thin, firm, fine and stable chromium-rich oxide film (protective film) formed...
The 2205 duplex stainless steel has a history of 80 years. Nitrogen is added to the 2205 stainless steel to improve the local corrosion resistance. The ferrite and austenite phases in its solid solution structure account for about half, and generally the least phase content is obtained. It also needs to reach 30%, so it has the performance characteristics of ferritic and austenitic stainless steels. Compared with austenitic 316L steel, 2205 duplex stainless steel has the following advantages. 1. The yield strength of 2205 dual-phase steel is more than double that of 316L austenitic stainless steel, and it has sufficient plasticity and toughness required for forming. The wall thickness of the pressure vessel manufactured by the 2205 stainless steel manufacturer is 30-50% lower than that of the 316L stainless steel pipe, which is conducive to reducing costs. 2. 2205 dual-phase steel has excellent resistance to stress corrosion cracking, especially in the marine environment containing chloride ions, stress corrosion is a prominent problem that austenitic stainless steel is difficult to solve. 3. The corrosion resistance of the common 2205 duplex steel in many media is due to the common 316L stainless steel, while the super duplex stainless steel has extremely high...
1. Smelting process: Basic principles of stainless steel smelting Unlike carbon steel production, stainless steel contains at least 10.5% Cr, so during decarburization reactions, reactions occur: Cr3O4+4[C]=3[Cr]+4CO reaction equilibrium constant Because in high Cr molten steel, Cr is preferentially oxidized than C. At normal smelting temperature, when C is below 0.03%, the equilibrium Cr is only about 4%; increasing the temperature can increase the equilibrium Cr content, but the refractory material is unbearable. For example, the temperature of molten steel with 18% Cr should reach above 1900 ℃, and a smelting method to reduce the partial pressure of CO was developed for this purpose. Stainless steel commonly used refining methods: Electric arc furnace (EF) direct smelting method, AOD (argon oxygen decarburization method), VOD (vacuum oxygen decarburization method), converter top low re-blowing method (K-OBM-S, K-BOP method, etc.), RH- The OB method is dominated by the AOD method and the VOD method. The two-step and three-step processes are used to smelt stainless steel, which can produce low-carbon and ultra-low-carbon stainless steel in large quantities, and the recovery rate of Cr also reaches a high level. 1) Several stainless steel smelting methods: u One-step method: EAF original electric furnace direct production process u...
Since the advent of stainless steel in the early 20th century, with the continuous development of its research and development and production technology, its standards have also been gradually established in various industrialized countries. The establishment and improvement of stainless steel standards will in turn promote the progress of stainless steel production technology. It plays an extremely important role in promoting the improvement of product quality and developing the market trade of stainless steel products. 1. China National (GB/T) Standard: u GB/T4237-2007 Stainless steel hot-rolled steel plate and strip uGB/T3280-2007 Stainless Steel Cold Rolled Steel Plate and Strip uGB/T4238-2007 Heat-resistant steel plates and strips uGB/T1220 stainless steel rod uGB/T8165 stainless steel clad steel plate and strip uGB/T20878-2007 Stainless steel and heat-resistant steel, grades and chemical composition uOther special stainless steel standards, etc. and various enterprise standards 2. Commonly used foreign standards (international general standards): uASTM A240 (M) Stainless Steel Plate (American Standard) u ASME A 240 (M) stainless steel plate (American Standard) u ASTM A 480 (M) stainless steel plate (American Standard) u JIS4305 stainless steel cold rolled steel plate (Japanese standard) u JIS4304 stainless steel hot-rolled steel plate (Japanese standard) uEN10028 Stainless Steel for Pressure Vessels (EU) uEN10088 General...
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