Classification of steel

 Classification of steel

       There are various classification methods of steel, and there are eight main methods:

　　1. Classified by quality  (1) General steel (phosphorus P≤0.045%, sulfur S≤0.050%)  (2) High-quality steel (both P and 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 (carbon C≤0.25%); b. medium carbon steel (carbon C≤0.25~0.60%); c. high carbon steel (carbon 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. Classified by forming method (1) Forged steel; (2) cast steel; (3) Hot rolled steel; (4) Cold drawn steel.

　　4. Classified by metallographic structure  (1) For annealing: a. hypoeutectoid steel (ferrite + pearlite); b. eutectoid steel (pearlite); c. hypereutectoid steel (pearlite + cementite); d. Tensitic steel (pearlite + cementite).  (2) For normalizing conditions: a. Pearlitic steel; b. Bainite steel; c. Martensitic steel; d. Austenitic steel.  (3) No phase change or partial phase change occurs.

　　5. Classified by purpose  (1) Steel for construction and engineering: a. General 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) Surface hardened structural steel: including carburizing steel, ammoniated steel, and surface quenching steel; (c) Easy-cut 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 function steel: a. Stainless acid-resistant steel; b. Heat-resistant steel: including anti-oxidation steel, heat-strength steel, valve steel; c. Electric heating alloy steel; d. Wear-resistant steel; e. Low-temperature steel ; f. Electrical steel.  (5) Steel for professional use—such as steel for bridges, steel for ships, steel for boilers, steel for pressure vessels, steel for agricultural machinery, etc.

　　6. General classification (1) General 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-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) 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 function 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. Classification by training method (1) According to furnace type a. Open hearth steel: (a) acidic open hearth steel; (b) basic open hearth steel. b. Converter steel: (a) acidic converter steel; (b) basic 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) According to the degree of deoxidation and pouring criteria: a. Boiling steel; b. Semi-killed steel; Killed steel; d. Special killed steel.

　　8. Classification according to shape (1) profiles (2) Plate (3) pipe (4) Four categories of metal products.