1. According to the main chemical composition, it can be divided into chromium stainless steel, 304 stainless steel pipe, chromium nickel stainless steel, chromium manganese nitrogen stainless steel, chromium nickel molybdenum stainless steel, ultra-low carbon stainless steel, high molybdenum stainless steel, high purity stainless steel, etc.; and Q2K9_ 8M)s4i7L7jL%]

Austenitic (a) stainless steel: austenitic stainless steel is marked with 200 and 300 series numbers. The microstructure is austenite. It is formed by adding appropriate nickel (the mass fraction of nickel is 8% ~ 25%) into high chromium stainless steel. 6x.p5^!@ M:N3s.l5z+x6C

1Cr18Ni9Ti(321)、0Cr18Ni10(304)、00Cr17Ni14M02(316L)2T! M(s%Y6e; d

Advantages: easy to weld, good plasticity (not easy to break), deformation, stability (not easy to rust), easy passivation. 5G/b9t9C#u

Disadvantages: but it is particularly sensitive to the medium containing cl- in the solution, and is prone to stress corrosion.

Ferritic (f) stainless steel: 400 series of digital representation. The internal microstructure of the product is ferrite, and the chromium content is within 11.5% - 32.0%. With the increase of chromium content, the acid resistance of chromium is improved. When molybdenum (MO) is added, the acid corrosion resistance and stress corrosion resistance can be improved. "A5]! B*f+]*Ze%B; G-|'H!`$ l

Advantages: high chromium content, good thermal conductivity, good stability and good heat dissipation. Disadvantages: but the mechanical and technological properties are poor. 1J8@&m*E+y8x

Purpose: it is mainly used for acid resistant structure with little force and used as anti-oxidation steel, such as stove, exhaust pipe (behind motorcycle)& S! H1E:Z4x;| V.a

Martensitic (m) stainless steel: 400 series of digital representation. Its microstructure is martensite. The chromium content in this kind of steel is 11.5% - 18.0%, but the highest content of carbon is 0.6%. The increase of carbon content improves the strength and hardness of steel. A small amount of nickel added to this kind of steel can promote martensite formation and improve its corrosion resistance. 1Cr13(410)、2Cr13(420)、3Cr13()、1Cr17Ni2()

Advantages: high carbon content and high hardness. Disadvantages: the plasticity and weldability of this kind of steel are poor（ M$R9I9o(q-s#[0J

Usage: mould, underground pipe, tool, cutting tool, tableware, bolt, nut. 2N#L! W5}&q; u

2. According to the performance characteristics and uses of steel, such as nitric acid (nitric acid) stainless steel, sulfuric acid resistant stainless steel, pitting resistant stainless steel, stress-resistant stainless steel, high-strength stainless steel, etc.

3. According to the functional characteristics of steel, such as low temperature stainless steel, non magnetic stainless steel, easy cutting stainless steel, superplastic stainless steel, etc.

4. Classification methods abroad: characteristics and uses of 200, 300, 400 series products（ 201, 202, 300, 301 are similar in material, mostly used for decorative materials) x8q! G/g%q&[,a%r%E

Series 200: austenitic stainless steel. Features: low Ni content, easy to rust. Rust removal: use bright paste, water-based bright paste, clean water, rust prevention: film protection liquid, water-based film protection liquid.

Purpose: stainless steel strip, used for decorative materials, stainless steel doors and windows, stainless steel stair handrails, anti-theft net, etc.

300 series: 304 stainless steel pipe austenitic stainless steel. Features: high Ni content and good corrosion resistance. Purpose: for industrial, chemical equipment, printing and dyeing equipment, etc. 7f({; c+X'@9g1D&A

Series 400: marooite, ferritic stainless steel. Features: no Ni, easy to rust. Rust proof, used in tableware, tools, cutting tools are more.

Duplex stainless steel

(duplex) ferritic martensitic steel stainless steel: 7Y / ~. [4O + V (@'p)

(duplex) martensite carbide steel stainless steel: /m; F-F"p/d5A3w3{*O1E1Z1|

(duplex) austenitic / Ferritic (A-F) stainless steel: its microstructure is austenite ferrite. Stainless steel with ferrite volume fraction less than 10% is a kind of steel developed on the basis of austenite steel/ M2K4t1s#M4g

(duplex) austenitic martensite (A-M) stainless steel:

Advantages: easy to form and weld, high strength (C can reach 100-150) and good thermal strength,: X1z - ^2a + P1 ': z$n4k7r0y

Disadvantages: however, because of the low chromium content and the precipitation of chromium carbide during heat treatment, the corrosion resistance is lower than that of standard austenitic stainless steel.

Purpose: at present, this kind of steel is mainly used in industrial production. It is not widely used in general mechanical manufacturing, and it is also included in classification as ultra-high strength steel š y $V $i'e:n9z4e0l

Precipitation hardening (PH) stainless steel: according to its structure, it can be divided into three types: precipitation hardening semi austenite type, precipitation hardening martensite type and precipitation hardening austenite type stainless steel. The structure of the steel is characterized by ferrite structure with austenite addition integral of 5% - 20% in the solid solution or annealing state（ d*F8U0N"V)U

Advantages and uses: this steel has good formability and good weldability, and can be used as super high strength material in nuclear industry, aviation and aerospace industry.