Classification of steel with basic knowledge of steel

In addition to iron and carbon, the main elements of steel include silicon, manganese, sulfur, and phosphorus. There are various classification methods of 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 (both P and S ≤ 0.035%)
(3) High-grade 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 content of alloy elements > 5-10%); c. High alloy steel (total content of alloy elements > 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. Hypo-eutectoid steel (ferrite + pearlite); b. eutectoid steel (pearlite); c. hypereutectoid steel (pearlite + cementite); d. Lai Tensitic steel (pearlite + cementite).
(2) Normalized state: a. pearlitic steel; b. bainitic steel; c. martensitic steel; d. austenitic steel.
(3) No phase change or partial phase change

5. Classification by use
(1) Steel for construction and engineering: a. ordinary carbon structural steel; b. low-alloy structural steel; c. reinforced steel.
(2) Structural steel:
a. Steel for machinery manufacturing: (a) quenched and tempered structural steel; (b) case-hardened structural steel: including carburized steel, ammonia-impregnated steel, and surface quenched steel; (c) free-cutting structural steel; (d) cold plasticity Steel for 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 tool steel.
(4) Special performance steel: a. stainless acid-resistant steel; b. heat-resistant steel: including oxidation-resistant steel, heat-strength steel, valve steel; c. electrothermal alloy steel; d. wear-resistant steel; e. low-temperature steel ; f. Electrical steel.
(5) Professional steel – such as steel for bridges, steel for ships, steel for boilers, steel for pressure vessels, steel for agricultural machinery, 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-grade high-quality steel)
a. Structural steel: (a) high-quality carbon structural steel; (b) alloy structural steel; (c) spring steel; (d) free-cutting 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 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 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 the degree of deoxidation and the pouring system
a. Boiling steel; b. Semi-killed steel; c. Killed steel; d. Special killed steel.