Classification of steel

The main elements of steel in addition to iron, carbon, silicon, manganese, sulfur, phosphorus and so on.

There are a variety of 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, S ≤0.035%)

(3) High quality steel (P≤0.035%, S≤0.030%)

2. Classified 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 alloying element content ≤5%); b. Medium alloy steel (total alloying element content > 5 ~ 10%); c. High alloy steel (total alloying 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 organization

(1) Annealed state: a. hypoeutectoid steel (ferrite + pearlite); b. Eutectoid steel (pearlite); c. Hypereutectoid steel (pearlite + cementite); d. Letenite steel (pearlite + cementite).

(2) Normalizing state: a. pearlite steel; b. Bainitic steel; c. Martensitic steel; d. austenitic steel.

(3) No phase transition or partial phase transition

5. Classification by use

(1) Construction and engineering steel: a. ordinary carbon structural steel; b. Low alloy structural steel; c. Steel reinforcement.

(2) Structural steel:

a. Steel for mechanical manufacturing: (a) tempered structural steel; (b) surface hardened structural steel: including carburized steel, ammoniated steel, surface hardened steel; (c) easy cutting structural steel; (d) Steel for cold plastic forming: 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 acid-resistant steel; b. Heat-resistant steel: including anti-oxidation steel, heat-strong steel, valve steel; c. Electrothermal 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. Ordinary 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 cutting steel; (e) Bearing steel; (f) 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) Steel for electrical purposes; (e) High manganese wear-resistant steel.

7. Classification by smelting method

(1) According to furnace type

a. Converter steel: (a) acid converter steel; (b) Basic Bessemer steel. Or (a) bottom blown Bessemer steel; (b) side-blown Bessemer steel; (c) Top blown converter steel.

b. Electric furnace steel: (a) electric furnace steel; (b) electroslag furnace steel; (c) induction furnace steel; (d) vacuum consumable furnace steel; (e) electron beam furnace steel.

(2) According to the degree of deoxidation and pouring system

a. boiling steel; b. Semi-killed steel; c. Killed steel; d. Special killing steel.