Steel is widely used in our life. We can see high-way road, bridge, airplane, cars, fence, shelf bracket, firepit, home décor and other products are made of steel. Steel is an iron-carbon alloy with a carbon content of 0.04%-2.3%. In order to ensure its toughness and plasticity, the carbon content generally does not exceed 1.7%. In addition to iron and carbon, the main elements of steel include silicon, manganese, sulfur, and phosphorus. There are various steel classification methods, and the main methods are as follows:
1. Steel is classified by quality
(1) Ordinary steel (P≤0.045%, S≤0.050%)
(2) High-quality steel material steel (P, S are both ≤0.035%)
(3) High quality steel (P≤0.035%, S≤0.030%)
2. , Classified by chemical composition
(1) Carbon steel: 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 alloying elements ≤5%); b. Medium alloy steel (total content of alloying elements>5~10%); c. High alloy steel (total content of alloying elements> 10%).
3. Steel materials are classified according to the forming method: (1) Forged steel; (2) Cast steel; (3) Hot rolled steel; (4) Cold drawn steel.
4. Steel is classified according to metallographic organization
(1) Annealed state: a. Hypoeutectoid steel (ferrite + pearlite); b. Eutectoid steel (pearlite); c. Over-eutectic steel precipitation (pearlite + cementite); d. ledeburite steel (pearlite + cementite).
(2) Normalizing: a. Pearlitic steel; b. Bainitic steel; c. Martensitic steel; d. Austenitic steel.
(3) Steel with no phase change or partial phase change 5. Classified by purpose
(1) Steel for construction and engineering: a. Ordinary carbon structural steel; b. Low alloy structural steel; c. Reinforced steel.
(2) Steel structural steel
a. Steel for machinery manufacturing: (a) Quenched and tempered structural steel; (b) Surface hardened structural steel: Including carburized steel, ammonia infiltrated steel, and surface hardening steel; (c) Free-cutting structural steel; (d) Cold plastic forming Steel: 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. Electric heating 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. General structural steel for specific purposes
(2) High-quality steel (including high-quality steel)
a. Steel structural steel: (a) high-quality carbon structural steel; (b) alloy structural steel; (c) spring steel; (d) free-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) electric heating alloy steel; (d) electrical steel; (e) high manganese wear-resistant steel.
7. Classified by smelting method
(1) According to furnace type
a. Open hearth steel: (a) acid open hearth steel; (b) basic open-hearth steel.
b. Converter steel: (a) acid converter steel; (b) alkaline converter steel. Or (a) bottom blown converter steel; (b) side blown converter steel; (c) top blown converter steel.
c. 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) Steel is divided according to the degree of deoxidation and pouring system
a. Boiling steel; b. Semi-killed steel; c. Killed steel;