First. Ferrous Metals, Steel and Nonferrous Metals
Before introducing the classification of steel, please briefly introduce the basic concepts of ferrous metals, steel and non-ferrous metals.
1. Ferrous metal is iron and iron alloy. Such as steel, pig iron, cast iron and so on. Steel and pig iron are based on iron, carbon as the main element of the alloy, collectively referred to as iron-carbon alloy. Pig iron is the iron ore into the blast furnace smelting products, mainly used for steel and manufacturing castings. The cast pig iron in the melting furnace melting, that is, cast iron (liquid), the cast iron cast into castings, this cast iron is called cast iron.
Ferroalloy is composed of iron and silicon, manganese, chromium, titanium and other elements of the alloy, ferroalloy is one of the raw materials of steel, steel in steel when the steel deoxidizer and alloying elements used.
2. The steel with iron into the steel furnace according to a certain process of melting, that is, steel. Steel products are steel ingots, cast slabs and cast directly into a variety of steel castings. Generally speaking, steel, generally refers to the rolling into a variety of steel steel. Steel is black metal but steel is not exactly equal to ferrous metal.
3. Non-ferrous metals, also known as non-ferrous metals, refers to the metal and alloys other than black metal, such as copper, tin, lead, zinc, aluminum and brass, bronze, aluminum alloy and bearing alloys. In addition, the industry also uses chromium, nickel, manganese, molybdenum, cobalt, vanadium, tungsten, titanium, etc., these metals are mainly used as alloy additives to improve the performance of metal, including tungsten, titanium, molybdenum and other Of the cemented carbide. These non-ferrous metals are known as industrial metals, in addition to precious metals: platinum, gold, silver and other rare metals, including radioactive uranium, radium and so on.
Second. The Classification of Steel
Steel is iron and carbon alloy with carbon content between 0.04% and 2.3%. In order to ensure its toughness and plasticity, carbon content is generally not more than 1.7%. The main elements of steel in addition to iron, carbon, there are silicon, manganese, sulfur, phosphorus and so on. Steel classification methods are varied, the main methods are as follows:
1. By quality classification
(1) Ordinary steel (P ≤ 0.045%, S ≤ 0.050%)
(2) High-quality steel (P, S are ≤ 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 (0.25 <C ≤ 0.60%); c. High carbon steel (C> 0.60%).
2) Alloy steel: a. Low alloy steel (alloying element content ≤ 5%) b. Medium alloy steel (alloying element content of 5 ~ 10%) c. High alloy steel (alloying element content> 10%).
3. According to the forming method classification: (1) Forged steel; (2) Cast steel; (3) Hot-rolled steel; (4) Cold drawn steel.
4. According to the microstructure (is the study of the internal structure of steel science) classification
(Pearlite + cementite) d. Leyer's steel (pearlite) (pearlite) c. Body + infiltration body).
2) Normalizing state: a. Pearlitic steel; b. Bainitic steel; c. Martensitic steel; d. Austenitic steel.
3) No phase change or partial phase change
5. According to use classification
1) Construction and engineering steel: a. Ordinary carbon structural steel; b. Low alloy structural steel; c. Reinforced steel.
2) Structural steel: a. Machinery for manufacturing steel: (a) Quenched and tempered structural steels; (b) Surface hardened structural steels: including carburized steel, ammonia steels, surface hardened steels; (c) Easily cut structural steels; (d) Cold forming steel: Steel, cold forging steel. 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 steel acid; b. Heat-resistant steel, including anti-oxidation steel, heat steel, valve steel; c. Electric alloy steel; d. Wear steel; e. Electrical steel
5) Professional steel - such as bridge steel, ship steel, boiler steel, pressure vessel steel, agricultural machinery and so on.
6. Comprehensive classification
(A) Q195; (b) Q215 (A, B); (c) Q235 (A, B, C); (d) Q255 (A, B); (b) e) Q275. b. Low alloy structural steel. c. General purpose structural steel for specific purposes
2) High quality steel (including high quality steel)
(a) High quality carbon structural steel; (b) Alloy structural steel; (c) Spring steel; (d) Easy to cut 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.
(b) Heat-resistant steel; (c) Electric alloy steel; (d) Electrical steel; (e) High manganese wear-resistant steel.
7. According to smelting method classification
1) By the furnace points
a. Oven steel (with air as oxidant): (a) Acid flat furnace steel; (b) Alkaline flat steel.
b. Converter steel (with oxygen as oxidant): (a) Acid converter steel; (b) Alkaline converter steel. Or (a) Bottom-blown converter steel; (b) Side-blown converter steel; (c) Top-blown converter steel.
(b) Electroslag furnace steel; (c) Induction furnace steel; (d) Vacuum consumption furnace steel; (e) Electron beam furnace steel; (b) Electroless furnace steel;
B) Semi-killed steel (deoxidation degree between boiling steel and sedimentary steel); c. Killed steel (deoxidation degree is more complete); b. Semi-killed steel (deoxidation degree between boiling steel and sedimentary steel) d. Special sedative steel (the most complete degree of deoxidation, high quality steel).
8. According to the shape classification: divided into: a. Profiles, b. Sheet, c. Pipe, d. Metal products four categories.
Heavy rail: more than 30 kg per meter weight of the rail (including the crane rail);
A rail of less than or equal to 30 kg per meter.
Large, medium and small sections: ordinary steel round bar, square steel, flat steel, hexagonal steel, I-beam, channel, equilateral and unequal angle steel and rebar.
Wire: 5-10 mm in diameter round bar and wire rod.
Cold-formed steel: steel or steel strip cold-formed steel.
High-quality profiles: high-quality steel round steel, square steel, flat steel, hexagonal steel.
Thin steel plate: steel plate with thickness equal to or less than 4 mm.
Medium and thick steel plate: thickness greater than 4 mm steel plate. Medium plate: thickness greater than 4mm less than 20mm); thick plate: thickness greater than 20mm less than 60mm; special plate: thickness greater than 60mm.
Strip: also called strip, is actually long and narrow and rolled into thin plate.
Electrical silicon steel sheet: also known as silicon steel sheet or silicon steel sheet.
Seamless steel pipe: with hot pressing, cold rolling (cold drawing or extrusion) and other methods of production of seamless steel pipe wall.
Welded steel pipe: the steel plate or strip crimping, and then welded steel pipe.
d. Metal products: including steel wire, wire rope, steel wire and so on.
What is special steel?
There is no uniform definition and concept of special steel. It is generally believed that special steel is steel which has special chemical composition, special craft production, special organization and performance, and can meet special needs. Compared with ordinary steel, special steel has a higher strength and toughness, physical properties, chemical properties, biocompatibility and process performance.
China and Japan, the European Union on the definition of special steel is relatively close to the special steel is divided into high-quality carbon steel, alloy steel, high alloy steel (alloying elements greater than 10%) three categories, including alloy steel and high alloy steel accounted for special steel production Of 70%. The main steel has special carbon structural steel, carbon tool steel, carbon spring steel, alloy spring steel, alloy structural steel, ball bearing steel, alloy tool steel, high alloy tool steel, high speed tool steel, stainless steel, , As well as high temperature alloys, precision alloys, electric alloys and so on. At present the world has nearly 2000 special steel grades, about 50,000 varieties specifications. In addition to a wide variety of special steel, the specifications also show different characteristics with ordinary steel. In addition to the board, tube, silk, belt, rod and profile, there are composite materials, surface alloying materials, surface treatment materials, precision forging materials, precision castings, powder metallurgy products.