What types of stainless steel are there?
Stainless steel type:
Stainless steel can be roughly classified according to use, chemical composition and metallographic structure.
Classified 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 refers to steel that is resistant to corrosion in the atmosphere and weakly corrosive media.
2. Acid-resistant stainless steel, which refers to steel that is resistant to 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 0 degrees Celsius. It is called ultra-low temperature steel that can be used below minus 196 degrees Celsius.
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 organization:
1. Austenitic stainless steel: As the name suggests, it is a stainless steel with austenitic structure at room temperature. When it contains Ni 8%~10%, Cr is about 18%, and C is about 0.1%, it has a stable austenite structure. Austenitic stainless steels are non-magnetic and have high toughness and plasticity. 201, 202, 301, 304, 316, 309, 321, etc. are austenitic stainless steels. Due to the comprehensive and good comprehensive properties of austenitic stainless steel, it has been widely used in various industries.
2. Ferritic stainless steel: It is a stainless steel mainly composed of ferrite in the use state. It has a body-centered cubic crystal structure with a chromium content of 11% to 30%. Generally does not contain nickel, and sometimes also contains a small amount of Mo, Ti, Nb and other elements. It has the characteristics of large thermal conductivity, small expansion coefficient, good oxidation resistance, and excellent stress corrosion resistance. It is mostly used in the manufacture of water vapor resistance, water resistance and oxidizing acid. Corroded parts.
3. Martensitic stainless steel: Stainless steel whose mechanical properties can be adjusted by heat treatment, in layman's terms, is a type of hardenable stainless steel. The typical grade is Cr13 type. The hardness after quenching is high, and different tempering temperatures have different combinations of strength and toughness. Standard martensitic stainless steels are: 403, 410, 414, 416, 416(Se), 420, 431, 440A, 440B and 440C types.
4. Austenite-ferritic duplex stainless steel: It is a stainless steel with austenite and ferrite structure accounting for about half of each. The Ni content is 3%~10%, and the Cr content is 18%~28%. Some steels also contain alloying elements such as Mo, Cu, Si, Nb, Ti, and N. This type of steel combines the characteristics of austenitic and ferritic stainless steels, while maintaining the 475°C brittleness of ferritic stainless steels, high thermal conductivity, and superplasticity. Duplex stainless steel has excellent pitting corrosion resistance and is a nickel-saving stainless steel.
5. Precipitation hardening stainless steel: Precipitation hardening stainless steel refers to the addition of different types and quantities of strengthening elements on the basis of the chemical composition of stainless steel, and different types and quantities of carbides, nitrides, and carbons are precipitated through the precipitation hardening process. Nitride and intermetallic compounds, a type of high-strength stainless steel that not only improves the strength of the steel but also maintains sufficient toughness, referred to as PH steel. Precipitation hardening stainless steel can be divided into three types: martensitic, semi-austenitic and austenitic according to the metallographic structure of its matrix.