Stainless steel tips
2016-09-06 18:33:28
In layman's terms, that is not easy to rust stainless steel, in fact, part of the stainless steel, both of stainless steel, but also acid resistance (corrosion resistance). Stainless steel and corrosion resistance of stainless steel is due to its chromium-rich oxide film on the surface (passivation film) is formed. This stainless steel and corrosion resistance is relative. Tests showed that the steel in the atmosphere, water and other weak medium and nitric acid oxidizing medium, the corrosion resistance of steel with chromium added water content and improve, when the chromium content reaches a certain percentage of the occurrence of corrosion resistance of steel mutation, namely rust from easy to rust, never corrosion to corrosion. Many classification of stainless steel. Classification by structure organization at room temperature, there are martensitic, austenitic, ferritic and duplex stainless steel; by major chemical composition, can basically be divided into chromium stainless steel and chrome-nickel stainless steel two systems; BY PURPOSE there are nitric acid-resistant stainless steel, acid-resistant stainless steel, water-resistant stainless steel, etc., can be divided into types by corrosion pitting corrosion of stainless steel, stress corrosion of stainless steel, resistance to intergranular corrosion of stainless steel; press features can be divided into no category magnetic stainless steel, free cutting stainless steel, cold steel, high strength stainless steel and so on. Because stainless steel has excellent corrosion resistance, formability, compatibility and a wide temperature range, toughness, and other characteristics, so get was widely used in heavy industry, light industry, household items and building decoration industry and other industries . Austenitic stainless steel having austenite stainless steel at room temperature. Cr steel containing about 18%, Ni 8% ~ 10%, while about 0.1% C, with a stable austenite. Austenitic chromium-nickel stainless steel including the famous steel and 18Cr-8Ni increase on this basis Cr, Ni content and adding Mo, Cu, Si, Nb, Ti and other elements developed series of high Cr-Ni steel. And non-magnetic austenitic stainless steel with high toughness and ductility, but lower strength, it is impossible to make it through the phase change hardening, can only be strengthened by cold working. Such as adding S, Ca, Se, Te and other elements, it has a good and easy machinability. In addition to this type of steel resistant to oxidizing acid medium corrosion, if it contains Mo, Cu and other elements are also resistant to the corrosive sulfuric acid, phosphoric acid and formic acid, acetic acid, urea and the like. Such steel when the carbon content less than 0.03% or containing Ti, Ni, can significantly improve their resistance to intergranular corrosion between. High silicon austenitic stainless steel concentrated nitric acid is willing to have good corrosion resistance. Since the austenitic stainless steel having a comprehensive and good overall performance, in all walks of life access to a wide range of applications. 316 and 316L stainless steel 316 and 317 stainless steel (317 stainless steel performance see below) is a stainless steel containing molybdenum species. 317 stainless steel is slightly clever molybdenum content in 316 stainless steel. Because molybdenum steel, the steel overall performance is better than 310 and 304 stainless steel, high temperature conditions, when the sulfuric acid concentration of less than 15% and greater than 85%, 316 stainless steel with a wide range of uses. 316 stainless steel and chloride also has good corrosion performance, it is usually used in the marine environment. The maximum carbon content of 0.03 316L stainless steel, and can be used for annealing need not be the maximum corrosion resistance but after soldering. Corrosion corrosion resistance than 304 stainless steel with good corrosion performance in the pulp and paper production process. 316 stainless steel and is also resistant to aggressive industrial atmosphere and marine erosion. Heat resistance in continuous use 1600 degrees and 1700 degrees below the continuous use of the 316 stainless steel has good resistance to oxidation. In the range of 800-1575 degrees, it is best not to effect continuous 316 stainless steel, 316 stainless steel but continuous use beyond this temperature range, the stainless steel has good heat resistance. Resistant stainless steel 316L carbide precipitation performance better than the 316 stainless steel can be used above temperature range. Heat treatment in the temperature range 1850-2050 ° annealed and then rapidly annealed and then rapidly cooled. 316 stainless steel can not be hardened to heat treatment. Welded 316 stainless steel has good weldability. It can be used with all standard soldering conditions. Welding with the purpose of, respectively 316Cb, 316L stainless steel or 309Cb filler rod or electrode welding. For optimum corrosion resistance, stainless steel welding section 316 need to be annealed after welding. If you use 316L stainless steel, it does not require annealing after welding. Typical uses of pulp and paper equipment heat exchangers, dyeing equipment, film processing equipment, pipelines, coastal areas outside the building materials. Ferritic stainless steel in the state to use ferrite-based stainless steel. Chromium content of 11% to 30%, with a body-centered cubic crystal structure. Such steel is generally not contain nickel, sometimes also contain small amounts of Mo, Ti, Nb wait elements such steel with large thermal conductivity, expansion coefficient, good oxidation resistance, excellent resistance to stress corrosion, are used for the manufacture Weathering , steam, water and oxidizing acid corrosion of parts. The existence of such steel plastic poor ductility and corrosion resistance after welding and other shortcomings significantly reduced, thus limiting its application. Refining technology (AOD or VOD) applications enable carbon, nitrogen and other elements greatly reduce the gap, thus making this type of steel is widely used. Austenitic - ferritic duplex stainless steel is austenitic and ferritic stainless steel accounts for about half of each organization. In the case of containing a low C, Cr content 18% ~ 28%, Ni content of 3% to 10%. Some steel further contains Mo, Cu, Si, Nb, Ti, N and other alloying elements. Both austenitic class steel and ferritic stainless steel features, higher compared with ferrite, ductility, toughness, brittle at room temperature, resistance to intergranular corrosion and welding performance were significantly improved, while maintaining iron ferritic stainless steel 475 ℃ brittleness and high thermal conductivity, with superplastic characteristics. Compared with the austenitic stainless steel, high strength and resistance to intergranular corrosion and chloride stress corrosion has significantly improved. Duplex stainless steel has excellent resistance to pitting corrosion, but also a section of nickel stainless steel. Martensitic stainless steel heat treatment can be adjusted by the mechanical properties of stainless steel, layman's terms, it is a class of hardened stainless steel. Typical grades for Cr13 type, such as 2Cr13, 3Cr13, 4Cr13 and so on. High hardness after pure fire, different tempering temperature with different combinations of strength and toughness, mainly used for steam turbine blades, cutlery, surgical instruments. According to differences in chemical composition, it can be divided into martensitic chromium martensitic stainless steel and martensitic chromium nickel steel categories. Depending on the organization and strengthening mechanism, it can be divided into martensitic stainless steel, martensitic and semi-austenitic (or semi-martensite) precipitation hardening stainless steel and maraging stainless steel.