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Steel is an iron-carbon alloy with a carbon content between 0.04% and 2.3%. In order to ensure its toughness and plasticity, the carbon content generally does not exceed 1.7%. Besides iron and carbon, the main elements of steel are silicon, manganese, sulfur and phosphorus. There are many ways to classify steel, and the main methods are as follows:

1, classified by quality

(1) Ordinary steel (2) High-quality steel (3) Advanced high-quality steel

2. Classification by chemical composition

(1) carbon steel: a. low carbon steel; B. medium carbon steel; C. high carbon steel

(2) Alloy steel: a. Low alloy steel; B. medium alloy steel; C. high alloy steel

3. Classification by molding method

(2) forged steel; (2) cast steel; (3) hot rolled steel; (4) Cold-drawn steel

4. Classification by purpose

(1) steel for building and engineering: a. ordinary carbon structural steel; B. low alloy structural steel; C. steel bars.

(2) Structural steel

A steel for machine building: (a) quenched and tempered structural steel; (b) Case-hardened structural steel: including carburized steel, ammoniated steel and case-hardened steel; (c) free-cutting structural steel; (d) Steel for cold plastic forming: including steel for cold stamping and steel for cold heading; B. spring steel; bearing steel

(3) Tool steel: a. Carbon tool steel; B. alloy tool steel; C. high-speed tool steel.

(4) Special performance steel: a. Stainless and acid-resistant steel; B. Heat-resistant steel: including oxidation-resistant steel, heat-resistant steel and valve steel; C. electrothermal alloy steel; D. wear-resistant steel; E. low temperature steel; Electrical steel.

(5) Professional steel-such as steel for bridges, ships, boilers, pressure vessels and agricultural machinery.

5. Comprehensive classification

(1) ordinary steel

A. carbon structural steel: (a) q195; (b) Q2 15(A、B)； (c) Q235(A、B、C)； Q255(A、B)； Question 275.

B. Low alloy structural steel

C. General structural steel for special purposes

(2) High-quality steel (including advanced high-quality steel)

A. structural steel: (a) high-quality carbon structural steel; (b) alloy structural steel; Spring steel; Free cutting steel; 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 steel and acid-resistant steel; Heat-resistant steel; Electrothermal alloy steel; (d) electrical steel; (e) High manganese wear-resistant steel.

6. Classification of smelting methods

(1) by furnace type

A. open hearth steel: (a) acidic open hearth steel; Alkaline open hearth steel.

B converter steel: (a) acidic converter steel; 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 furnace steel; Electroslag furnace steel; Induction furnace steel; (d) Vacuum consumable furnace steel; (e) electron beam furnace steel.

(2) according to deoxidation degree and gating system

. Boiling steel; B. semi-killed steel; C. killed steel; Special killed steel.

7. Classification by shape

Can be divided into four categories: A. Profile B. Plate C. Pipe D. Metal products.

A. Personal data:

Heavy rails, rails weighing more than 30 kilograms per meter (including crane rails); Light rail, a rail with a weight of less than or equal to 30 kg per meter.

Large profiles: ordinary round steel, square steel, flat steel, hexagonal steel, I-beam, channel steel, equilateral and unequal angle steel and rebar, etc. Divided into large, medium and small steel according to size.

Wire rod: round steel and wire rod with a diameter of 5-10 mm.

Cold-formed section steel: section steel made of cold-formed section steel or steel strip.

High-quality profiles: high-quality round steel, square steel, flat steel, hexagonal steel, etc.

B. plate;

Thin steel plate with a thickness of 4 mm or less.

Thick steel plate, steel plate with thickness greater than 4 mm, can be divided into medium plate (thickness greater than 4 mm but less than 20 mm), thick plate (thickness greater than 20 mm but less than 60 mm) and extra-thick plate (thickness greater than 60 mm).

Steel strip, also called strip steel, is actually a long and narrow steel sheet supplied in rolls.

Electrical silicon steel sheet, also called silicon steel sheet or silicon steel sheet.

C. pipelines:

Seamless steel pipe is a seamless steel pipe produced by hot rolling, hot rolling-cold drawing or extrusion.

Welded steel pipe, which is formed by curling steel plate or steel strip and then welding.

D. Metal products

Including steel wire, steel wire rope, steel strand, etc.