Classification of steel

There are various classification methods for steel, 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 and 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 content of alloy elements ≤ 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. pearlite steel; b. Bainitic steel; c. Martensitic steel; d. Austenitic steel;

 (3) No phase transition or partial phase transition.

5. Classification by purpose

 (1) Steel for construction and Engineering: A. ordinary carbon structural steel; b. Low alloy structural steel; c. Steel reinforcement.

 (2) Structural steel:

a. Steel for mechanical manufacturing: (a) quenched and tempered structural steel; (b) Surface hardened structural steel: including carburized steel, ammoniated steel and steel for surface quenching; (c) Easy to cut structural steel; (d) Steel for cold plastic forming: including steel for cold stamping and steel for cold heading

b. Spring steel

c. Bearing steel

 (3) Tool steel: A. carbon tool steel; b. Alloy tool steel; c. High speed steel tools.

 (4) Special performance steel: A. stainless and acid resistant steel; b. Heat resistant steel: including oxidation resistant steel, heat 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 steel for specific purposes

 (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 to cut steel; (e) Bearing steel; (f) Special purpose high-quality structural steel.

b. Tool steel: (a) carbon tool steel; (b) Alloy tool steel; (c) High speed tool steel.

c. Special performance steel: (a) stainless and acid resistant steel; (b) Heat resistant steel; (c) Electric heating alloy steel; (d) Electrical steel; (e) High manganese wear resistant steel.

7. Classification by smelting method

 (1) By furnace type

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. Electric furnace steel: (a) electric arc furnace 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. Boiling steel;

b. Semi killed steel;

c. Killed steel;

d. Special killed steel