Basic knowledge of material steel classification

20 17 basic knowledge of material industrial steel classification

Steel has a wide range of uses and varieties. According to the different cross-sectional shapes, steel products are generally divided into four categories: profiles, plates, pipes and metal products. Steel is a material with certain shape, size and properties, which is made of ingot, billet or steel through pressure processing. Then, the following is the basic knowledge of material steel classification that I share with you. Welcome to read and browse.

I ferrous metals, steel and non-ferrous metals

Before introducing the classification of steel, briefly introduce the basic concepts of ferrous metal, steel and nonferrous metal.

1, ferrous metals refer to iron and ferroalloys. Such as steel, pig iron, ferroalloy, cast iron, etc. Both steel and pig iron are alloys based on iron and with carbon as the main additive element, which are collectively called iron-carbon alloys. Pig iron refers to the products made of iron ore smelted by blast furnace, which is mainly used for steelmaking and casting. Pig iron is melted in a melting furnace to obtain cast iron (liquid), and the liquid cast iron is cast into a casting. This kind of cast iron is called cast iron. Ferroalloy is an alloy composed of iron, silicon, manganese, chromium, titanium and other elements. Ferroalloy is one of the raw materials for steelmaking, which is used as deoxidizer and alloying element additive for steel.

2. Put pig iron for steelmaking into a steelmaking furnace and smelt it according to a certain process to obtain steel. Iron and steel products include direct casting of steel ingots, continuous casting billets and various steel castings. Generally speaking, steel refers to steel rolled into various kinds of steel. Steel belongs to ferrous metal, but steel is not completely equal to ferrous metal.

3. Non-ferrous metals, also known as non-ferrous metals, refer to metals and alloys other than ferrous metals, such as copper, tin, lead, zinc, aluminum, brass, bronze, aluminum alloys and bearing alloys. In addition, chromium, nickel, manganese, molybdenum, cobalt, vanadium, tungsten and titanium are also used in industry. These metals are mainly used as alloy additives to improve the properties of metals, among which tungsten, titanium and molybdenum are mostly used to produce cemented carbide for cutting tools. These nonferrous metals are called industrial metals, in addition to precious metals: platinum, gold, silver and rare metals, including radioactive uranium and radium.

Second, the classification of steel

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 (P? 0.045%，S？ 0.050%)

(2) high-quality steel (both P and S? 0.035%)

(3) 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 alloying elements >; 5 ~10%) C. high alloy steel (total content of alloying elements >; 10%)。

3. Classification according to forming mode: (1) forged steel; (2) cast steel; (3) hot rolled steel; (4) cold-drawn steel bars.

4, according to the metallographic organization classification

(1) A. hypoeutectoid steel (ferrite+pearlite) B. eutectoid steel (pearlite) C. hypereutectoid steel (pearlite+cementite) D. ledeburite steel (pearlite+cementite).

(2) normalizing: a. pearlite steel; B. bainite steel; C. martensitic steel; Austenite steel.

(3) No phase change or partial phase change.

5. 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; ? Free-cutting structural steel; (d) Steel for cold plastic 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 and acid-resistant steel B. Heat-resistant steel includes oxidation-resistant steel, heat-resistant steel and valve steel C. Electrothermal alloy steel; D. wear-resistant steel; E. low temperature steel; F. electrical steel

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

6. Comprehensive classification

(1) ordinary steel

A. carbon structural steel: (a) q195; (b) Q2 15(A、B)； ? 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; ? 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.

7. 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; ? 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

A. boiling steel; B. semi-killed steel; C. killed steel; Special killed steel.

8. According to the material shape, it can be divided into four categories: type, plate, tube and silk.

1. Type of section steel There are many kinds of steel, which are solid strip steel with certain cross-sectional shape and size. According to different cross-section shapes, it can be divided into simple cross-section and complex cross-section. The former includes round steel, square steel, flat steel, hexagonal angle steel and angle steel; The latter includes rail, I-beam, channel steel, window frame steel and special-shaped steel. Small round steel with a diameter of 6.5-9.0mm is called wire rod.

B, steel plate is a kind of flat steel, with large width-thickness ratio and large surface area. According to different thickness, thin plate (thickness% 26lt4mm), medium plate (thickness 4-25mm) and thick plate (thickness% 26gt25mm) are divided into three types. Steel strip belongs to the category of steel plate.

C, steel pipe is a hollow section of strip steel. According to their different cross-sectional shapes, they can be divided into round pipes, square pipes, hexagonal pipes and various steel pipes with special cross-sections. According to the different processing technology, it can be divided into seamless steel pipe and welded steel pipe.

D steel wire steel wire is also a cold-worked product of steel wire. According to different shapes, it can be divided into round steel wire, flat steel wire and triangular steel wire. Steel wire is not only used directly, but also used to produce steel wire rope, steel grain line and other products.

9, in order to facilitate the procurement, ordering and management, China currently divides steel into sixteen varieties:

Category description

Profile heavy rail weighs more than 30 kg per meter (including overweight machine rail)

Light rail with a weight of less than or equal to 30 kg per meter.

Large section steel: ordinary steel, round steel, square steel, flat steel, hexagonal steel, I-beam, channel steel, equilateral and unequal angle steel and rebar. According to size, it is divided into large, medium and small.

medium section steel

Small steel

Round steel and wire rod with wire diameter of 5- 10 mm

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

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

Other steel products include heavy rail fittings, axle blanks, tires, etc.

Steel plate with a thickness of 4 mm or less.

Steel plate with thickness greater than 4 mm

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

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

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

Seamless steel tubes for pipes are produced by hot rolling, hot rolling, cold drawing or extrusion.

Welded steel pipe The steel plate or steel strip is curled and then welded into a steel pipe.

Metal products Metal products include steel wire, steel wire rope, steel strand, etc.

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