Besides iron and carbon, the main elements of steel are silicon, manganese, sulfur and phosphorus.
The classification methods of steel are various, and the main methods are as follows:
1. Classification by quality
(1) Ordinary steel (P ≤ 0.045%, s ≤ 0.050%)
(2) High quality steel (P, s ≤ 0.035%)
(3) High quality steel (P ≤ 0.035%, s ≤ 0.030%)
2. Classification by chemical composition
(1) Carbon steel: A. low carbon steel (C ≤ 0.25%); B. medium carbon steel (C ≤ 0.25-0.60%); C. high carbon steel (C ≤ 0.60%).
(2) Alloy steel: A. low alloy steel (total alloy element content ≤ 5%); B. medium alloy steel (total alloy element content > 5-10%); C. high alloy steel (total alloy element content > 10%).
3. Classification by forming method
(1) Forged steel; (2) cast steel; (3) hot rolled steel; (4) cold drawn steel.
4. Classification by metallographic structure
(1) Annealed: A. hypoeutectoid steel (ferrite + pearlite); B. eutectoid steel (pearlite); C. hypereutectoid steel (pearlite + cementite); D. ledeburite steel (pearlite + cementite).
(2) Normalized: A. pearlitic steel; B. bainitic steel; C. martensitic steel; D. austenitic steel.
(3) Having no or partial transformation
5. Classification by application
(1) Construction and engineering steel: A. ordinary carbon structural steel; B. low alloy structural steel; C. reinforced steel.
(2) Structural steel:
a. Mechanical manufacturing steel: (a) quenching and tempering structural steel; (b) surface hardening structural steel: including carburizing steel, ammoniating steel and surface quenching steel; (c) easy cutting structural steel; (d) cold plastic forming steel: including cold stamping steel and cold heading steel.
b. Spring steel
c. Bearing steel
(3) Tool steel: A. carbon tool steel; B. alloy tool steel; C. high speed tool steel.
(4) Special performance steel: A. stainless and acid resistant steel; B. heat resistant steel: including anti-oxidation steel, hot strength steel and air valve steel; C. electric heating alloy steel; D. wear resistant steel; e. low temperature steel; F. electrical steel.
(5) Professional steel, such as bridge steel, ship steel, boiler steel, pressure vessel steel, agricultural machinery steel, etc.
6. Comprehensive classification
(1) Ordinary steel
a. Carbon structural steel: (a) Q195; (b) Q215 (a, b); (c) Q235 (a, B, c); (d) q255 (a, b); (E) Q275.
b. Low alloy structural steel
c. General structural steels for specific applications
(2) High quality steel (including high quality steel)
a. Structural steel: (a) high quality carbon structural steel; (b) alloy structural steel; (c) spring steel; (d) easy cutting steel; (E) bearing steel; (f) high quality structural steel for specific purposes.
b. Tool steel: (a) carbon tool steel; (b) alloy tool steel; (c) high speed tool steel.
c. Special performance steel: (a) stainless acid resistant steel; (b) heat resistant steel; (c) electrothermal alloy steel; (d) electrical steel; (E) high manganese wear-resistant steel.
7. Classification by smelting method
(1) According to the type of furnace
a. Converter steel: (a) acid converter steel; (b) basic converter steel. Or (a) bottom blown converter steel; (b) side blown converter steel; (c) top blown converter steel.
b. EAF steel: (a) EAF steel; (b) electroslag furnace steel; (c) induction furnace steel; (d) vacuum consumable furnace steel; (E) electron beam furnace steel.
(2) According to deoxidation degree and pouring system
a. The results show that there are three kinds of steels: rimmed steel; B. semi killed steel; C. killed steel; D. special killed steel.