Stainless steel can be roughly classified according to its use, chemical composition and metallographic structure.
Classification by use:
Stainless steel can be divided into four categories, namely, stainless steel, acid-resistant stainless steel, heat-resistant stainless steel and low-temperature stainless steel.
1, stainless steel, which is corrosion-resistant in the atmosphere and weakly corrosive medium.
2, acid-resistant stainless steel, which refers to steel that can resist corrosion in various strongly corrosive media.
3, heat-resistant stainless steel refers to stainless steel with high oxidation resistance and high enough high-temperature strength at high temperature.
4, low-temperature stainless steel, is an alloy steel suitable for applications below ℃, which can be used below minus 196℃ and is called ultra-low temperature steel.
classified by chemical composition:
1. CR series: ferrite series, martensite series
2.CR-NI series: austenite series, abnormal series, precipitation hardening series.
Classification by metallographic structure:
1. Austenitic stainless steel: As the name implies, it is stainless steel with austenite structure at room temperature. When it contains 8% ~ 1% Ni, 18% Cr and .1% C, it has a stable austenite structure. Austenitic stainless steel is nonmagnetic and has high toughness and plasticity. 21, 22, 31, 34, 316, 39 and 321 are austenitic stainless steels. Austenitic stainless steel has been widely used in all walks of life because of its comprehensive and good comprehensive properties.
2. ferritic stainless steel: it is a stainless steel with ferrite structure in use. It has a body-centered cubic crystal structure and contains 11%~3% chromium. Generally, it does not contain nickel, and sometimes it contains a small amount of elements such as Mo, Ti, Nb, etc. It has the characteristics of large thermal conductivity, small expansion coefficient, good oxidation resistance and excellent stress corrosion resistance, and is mostly used to manufacture parts that are resistant to water vapor, water and oxidative acid corrosion.
3. Martensite stainless steel: stainless steel whose mechanical properties can be adjusted by heat treatment. Generally speaking, it is a kind of hardenable stainless steel. The typical brand is Cr13. The hardness after quenching is high, and different tempering temperatures have different combinations of strength and toughness. The standard martensitic stainless steels are: 43, 41, 414, 416, 416(Se), 42, 431, 44A, 44B and 44C.
4. Austenite-ferrite duplex stainless steel: it is a stainless steel with about half austenite and half ferrite structure. Ni content is 3%~1% and Cr content is 18%~28%. Some steels also contain alloying elements such as Mo, Cu, Si, Nb, Ti, N, etc. This kind of steel has the characteristics of both austenitic and ferritic stainless steel, while maintaining the brittleness of ferritic stainless steel at 475℃, high thermal conductivity and superplasticity. Duplex stainless steel is a nickel-saving stainless steel with excellent pitting corrosion resistance.
5. precipitation hardening stainless steel: precipitation hardening stainless steel refers to a kind of high-strength stainless steel with different types and quantities of strengthening elements added to the chemical composition of stainless steel, and different types and quantities of carbides, nitrides, carbonitrides and intermetallic compounds are precipitated through precipitation hardening process, which not only improves the strength of steel but also maintains sufficient toughness, and is referred to as PH steel for short. Precipitation hardening stainless steel can be divided into martensite type, semi-austenite type and austenite type according to the metallographic structure of its matrix.
Wuxi lepei metal material co., ltd mainly sells 2 series (21/22)/ 3 series (34 34 L 316 L 316 Ti 321 34 J1 31 S 39 S 347 h) 4 series (43 444 41 S) (225 257 C276 94 L 254 SMOC4) series, width 1 mm-1219 mm-15 mm-18 mm-.