According to the concept, steel has the following material classifications. Production method, chemical composition, there are different material classifications.
1 The concept of steel: Steel is a steel ingot, billet, or steel that is press-worked into the various shapes, sizes, and properties I need.
With a wide range of applications and varieties, steel is an essential and important material for national construction and the realization of the four modernizations. According to the different section shapes, steel is generally divided into four categories: profiles, plates, pipes and metal products. Section steel, small section steel, steel cold-formed section steel, high-quality section steel, wire rod, medium and thick steel plate, thin steel plate, electrical silicon steel sheet, strip steel, seamless steel pipe steel, welded steel pipe, metal products and other varieties.
2 Production methods of steel
Plastic deformation of the processed steel (bill, ingot, etc.). According to the processing temperature of the steel, it can be divided into two types: cold working and hot working. The main processing methods of steel are: most of the processing of steel is processed by pressure.
A press working method with increased length, rolling: passing a steel metal blank through a gap (various shapes) of a pair of rotating rolls reduces the cross-section of the material due to the compression of the rolls. This is the most commonly used production method for producing steel, mainly used to produce steel profiles, plates and pipes. Cold-rolled and hot-rolled.
It is often used for the production of large-sized materials, billets and other materials with larger cross-sectional dimensions. Forged Steel: A press working method that uses the reciprocating impact of a hammer or the pressure of a press to change the billet to the shape and size I want. Generally divided into free forging and die forging.
Drawing steel: The processing method of drawing rolled metal billets (forms, pipes, products, etc.) through die holes to reduce the cross-section and increase the length is mostly used for cold working.
Apply pressure at one end, squeeze: The steel holds the metal inside a closed squeeze Jane. A processing method for extruding metal from a specified die hole to obtain a finished product with the same shape and size, mostly used for the production of non-ferrous metal steel
1. Ferrous metals, steel and non-ferrous metals
Before introducing the classification of steel, briefly introduce the basic concepts of ferrous metals, steel steel and non-ferrous metals.
Metallurgical materials produce alloys with carbon as the main additive element, 1 ferrous metals refer to alloys of iron and iron. Such as steel, pig iron, ferroalloy, cast iron, etc. Both steel and pig iron are based on iron steel. Collectively referred to as iron-carbon alloys.
Mainly used for steelmaking and steel castings. Casting pig iron is smelted in an iron melting furnace, and pig iron refers to a product made by smelting iron ore in a blast furnace. That is, cast iron (liquid) is obtained and the liquid cast iron is cast into casting steel, which is called cast iron.
Ferroalloy is one of the raw materials for steelmaking. Ferroalloy is an alloy composed of iron and silicon, manganese, chromium, titanium and other elements. It is used as a deoxidizer and an alloying element additive for steel during steel making.
That is to get steel. Steel products include ingots, continuous casting billets and direct steel casting into various steel castings. Usually speaking of steel, 2 put the pig iron for steelmaking into the steelmaking furnace and smelt it according to a certain process. Generally refers to steel rolled into various steels. Steel Steel is a ferrous metal but steel is not exactly equal to ferrous metal.
Refers to metals and alloys other than ferrous metals, 3 steel non-ferrous metals are also known as non-ferrous metals. Such as copper, tin, lead, zinc, aluminum and brass, bronze, aluminum alloy and bearing alloy. In addition, chromium, nickel, manganese, molybdenum, cobalt steel, vanadium, tungsten, titanium, etc. are also used in industry. These metals are mainly used as alloy additions to improve the performance of metals. Among them, tungsten, steel titanium, molybdenum, etc. are mostly used for production Carbide for cutting tools. The above non-ferrous metals are called industrial metals. In addition to steel, there are precious metals: platinum, gold, silver, etc. and rare metals, including radioactive uranium, radium and other steels.
2. Classification of steel materials
The carbon content generally does not exceed 1.7%. Except for iron and carbon, the main elements of steel are iron-carbon alloys whose carbon content is between 0.04% and 2.3%. In order to ensure its toughness and plasticity. There are also silicon, manganese, sulfur, phosphorus and so on. 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 (PS all ≤0.035%
3 High-grade high-quality steel (P≤0.035%S≤0.030%
2. Classification 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 Steels are classified according to forming methods: 1 forged steel; 2 cast steel; 3 hot rolled steel; 4 cold drawn steel.
4 Steels are classified by metallographic structure
1 annealed state a. Hypo-eutectoid steel (ferrite + pearlite); b. eutectoid steel (pearlite); c. hypereutectic steel (pearlite + cementite); d. ledeburite Steel (Pearlite + Cementite)
2 normalized state a. pearlitic steel; b. bainitic steel; c. martensitic steel; d. austenitic steel.
3 Steels with no phase transformation or partial phase transformation 5 Classification by use
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 case-hardened structural steel: including carburized steel, ammonia-impregnated steel, and surface quenching steel; c free-cutting structural steel; d cold plastic forming steel: including cold stamping Steel, cold heading 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 acid-resistant steel; b. heat-resistant steel: including oxidation-resistant steel, heat-strength steel, valve steel; c. electrothermal 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: aQ195; bQ215AB; cQ235ABC; dQ255AB; eQ275
b. Low alloy structural steel
c. Ordinary structural steel for specific purposes
2 high-quality steel (including high-grade 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 Classification by smelting method
1 According to the furnace type
a. Open hearth steel: a acid open hearth steel; b basic open hearth steel.
b. Converter steel: a acid 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 Steels are classified according to the degree of deoxidation and pouring system
a. Boiling steel; b. Semi-killed steel; c. Killed steel; d. Special killed steel.
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