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...
The stainless characteristic of stainless steel is due to the special passivation protective film on the surface of the steel plate. First, the corrosion resistance mechanism of stainless steel, that is, the theory of passivation film, is briefly introduced. The so-called passive film is a thin film mainly composed of Cr2O3 on the surface of stainless steel. Due to the existence of this film, the corrosion of the stainless steel substrate in various media is hindered, and this phenomenon is called passivation. There are two cases for the formation of this passivation film. One is that stainless steel itself has the ability of self-passivation, and this self-passivation ability is accelerated with the increase of chromium content. Another broad formation condition is that stainless steel forms a passivation film in the process of being corroded in various aqueous solutions (electrolytes), which hinders corrosion. Generally, the corrosion types of stainless steel are divided into two categories: uniform corrosion and local corrosion. With the popularization of stainless steel in people’s lives, a new corrosion type – “rust” is derived. 1. Uniform corrosion Uniform corrosion means that all the exposed metal surfaces in the corrosive environment undergo electrochemical or chemical reactions and are uniformly...
At the end of the last century, Japanese stainless steel manufacturers found through research that adding a certain antibacterial metal to stainless steel, after proper heat treatment, can obtain stainless steel with long-term stable antibacterial properties. In 1998, Rixin Iron and Steel Company successfully developed ferritic antibacterial stainless steel NSSAM1, martensitic antibacterial stainless steel NSSAM2 and austenitic antibacterial stainless steel NSSAM3, forming a copper-containing antibacterial stainless steel series. In the same year, Kawasaki Steel successfully developed silver-containing antibacterial stainless steel. The Stainless Steel Branch of Baosteel Co., Ltd. officially established the project in January 2005 under the above-mentioned market and technical background, and started the research and development of ferritic antibacterial stainless steel 430Cu product characteristics. Copper, and in the manufacturing process, special heat treatment is adopted, so that the stainless steel can evenly disperse the fine copper precipitates Fe-Cu from the surface to the interior, so that the stainless steel can obtain good antibacterial and sterilizing properties while ensuring its basic performance. performance. 430Cu maintains its original mechanical properties, corrosion resistance and good cold and hot working properties, and its strength is higher than that of ordinary 430 stainless steel, and when the elongation properties are equivalent, the cold...
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