Stainless steel

Generally speaking, stainless steel is not easy to rust steel, in fact, part of the stainless steel, both rust and acid resistance (corrosion resistance). Stainless steel stainless steel and corrosion resistance is on the surface of chromium rich oxide film (film) formation. The corrosion resistance and corrosion resistance are relative. The test shows that the steel in the atmosphere, water and other medium and weak acid oxidizing medium, the corrosion resistance increased with the increase of water content of chromium in steel, when the chromium content reaches a certain percentage, the steel corrosion resistance mutation from rust to rust, corrosion and corrosion resistance to never. Stainless steel classification methods. According to the organizational structure of classification at room temperature, a martensitic, Austenitic, Ferritic and duplex stainless steel; according to the classification of the main chemical components, basically can be divided into chromium and chromium nickel stainless steel two systems; by use of minute nitric acid resistant stainless steel, stainless steel, stainless steel corrosion resistance to sulfuric acid and so on, according to the corrosion resistance the type can be divided into stainless steel pitting corrosion, stress corrosion resistant stainless steel, intergranular corrosion resistant stainless steel; according to the features of classification can be divided into non magnetic stainless steel, stainless steel, stainless steel, free cutting low temperature high strength stainless steel and so on. Because the stainless steel material with excellent corrosion resistance, formability, and compatibility in a wide temperature range, strong toughness characteristics, so get widely used in heavy industry, light industry, supplies industry and construction decoration industry.

austenitic stainless steel

Austenitic stainless steel at room temperature. Steel containing Cr about 18%, Ni 8%~10%, C about 0.1%, with stable austenite structure. Austenitic chromium nickel stainless steel, including the famous 18Cr-8Ni steel and the increase of Cr, Ni content and the addition of Mo, Cu, Si, Nb, Ti and other elements of the development of high Cr-Ni series steel. Austenitic stainless steel is non-magnetic and has high toughness and plasticity, but the strength is low, it can not be strengthened by phase transformation, can only be strengthened by cold processing. Such as adding S, Ca, Se, Te and other elements, it has good machinability. This kind of steel in addition to oxidizing acid medium corrosion, if contain Mo, Cu and other elements can also be resistant to sulfuric acid, phosphoric acid and formic acid, acetic acid, urea and other corrosion. If the carbon content of the steel is lower than 0.03% or Ti, Ni, it can significantly improve the intergranular corrosion resistance. The high silicon austenitic stainless steel has good corrosion resistance. Austenitic stainless steel has been widely used in all walks of life due to its comprehensive and good comprehensive properties.

Ferritic stainless steel

Ferritic stainless steel in use. Chromium content in 11%~30%, with body centered cubic crystal structure. This kind of steel does not contain nickel, sometimes also contain a small amount of Mo, Ti, Nb when the elements of this kind of steel with high heat conductivity, low expansion coefficient, good oxidation resistance and anti stress excellent characteristics of stress corrosion, used formanufacturingthecorrosionresistanceofthe atmosphere, water vapor, waterandoxidizing parts. This kind of steel has many disadvantages, such as poor plasticity, low ductility and corrosion resistance, which limits its application. The application of external refining technology (AOD or VOD) can reduce the gap elements such as carbon and nitrogen, which makes the steel widely used.

Austenite ferrite duplex stainless steel

Austenite and ferrite are about half of the stainless steel. In the case of low C content, the content of Cr was 18%~28%, and the content of Ni was 3%~10%. Some steel also contains Mo, Cu, Si, Nb, Ti, N and other alloying elements. This kind of steel with austenite and ferrite stainless steel body, compared with ferrite, the plasticity and toughness are higher, no room temperature brittleness, intergranular corrosion resistance and welding performance was significantly improved, while also maintaining a ferritic stainless steel 475 DEG C brittleness and high thermal conductivity, superplasticity etc.. Compared with austenitic stainless steel, high strength and intergranular corrosion resistance and chloride stress corrosion are obviously improved. Duplex stainless steel has excellent corrosion resistance, is also a kind of nickel stainless steel.

Martensitic stainless steel

The mechanical properties of stainless steel can be adjusted by heat treatment, in general, it is a class of hardened stainless steel. Typical brand for Cr13, such as 2Cr13, 3Cr13, 4Cr13, etc.. After the fire, the hardness is high, and the tempering temperature has different strength and toughness combination. According to the differences in chemical composition, martensitic stainless steel can be divided into martensite and martensite chromium chromium nickel steel two. According to the difference of microstructure and strengthening mechanism, it can also be divided into martensite stainless steel, martensite and semi austenite (or semi martensite) precipitation hardening stainless steel and Maraging Stainless steel.