Concept and classification of steel
Steel is a material of certain shape, size and performance made of ingot, billet or steel through pressure processing. Most steel products are processed through pressure processing to make the processed steel (billet, ingot, etc.) produce plastic deformation. According to different steel processing temperatures, it can be divided into cold processing and hot processing.
Material introduction
Steel: It refers to the material of various shapes, sizes and properties required by the processing of ingots, billets or steels.
Steel products are generally divided into four categories: profiles, plates, pipes and metal products, and also into heavy rail, light rail, large section steel, medium section steel, small section steel, steel cold-formed section steel, high-quality section steel, wire rod, medium thick steel plate, thin steel plate, silicon steel sheet for electrical purposes, strip steel, seamless steel pipe steel, welded steel pipe, metal products and other varieties.
features
ferrous metal
Ferrous metals mainly refer to iron, manganese, chromium and their alloys.
steel
The pig iron for steelmaking is put into the steelmaking furnace for smelting according to a certain process to obtain steel.
Non ferrous metals
Metals other than ferrous metals are called nonferrous metals, such as copper, tin, lead, zinc, aluminum, brass, bronze, aluminum alloys and bearing alloys.
classification
Finished materials
Building materials - deformed steel bar, wire rod, spiral, round steel
Pipe material - seamless pipe, welded pipe
Plate - cold and hot rolled plate/coil, medium plate, color coated plate (galvanized plate, color coated plate, tinplate, aluminum zinc plated steel plate), silicon steel, strip steel
Profiles - I angle groove, H-shaped steel, square steel, flat steel, bulb flat steel
Special steel
Including structural steel, tool steel, die steel, spring steel, bearing steel, cold heading steel, hard wire
Steel is a ferrocarbon alloy with carbon content between 0.0218% and 2.11%. To ensure its toughness and plasticity, the carbon content generally does not exceed 1.7%. In addition to iron and carbon, the main elements of steel include silicon, manganese, sulfur, phosphorus, etc. There are various classification methods for steel, and the main methods are as follows:
1. Classified by quality
Ordinary steel: (P ≤ 0.045%, S ≤ 0.050%);
High quality steel: (P, S ≤ 0.035%);
High quality steel: (P ≤ 0.035%, S ≤ 0.030%).
2. Classification by chemical composition
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%).
Low alloy steel (total alloy element content<5%); b. Medium alloy steel (5% ≤ total content of alloy elements ≤ 10%); c. High alloy steel (total alloy element content>10%).
3. Classification according to forming method: (1) forged steel; (2) Cast steel; (3) Hot rolled steel; (4) Cold drawn steel.
4. Classification according to metallographic structure
Annealed state: a. hypoeutectoid steel (ferrite+pearlite); b. Eutectoid steel (pearlite); c. Hypereutectoid steel (pearlite+cementite); d. Ledeburite steel (pearlite+cementite).
Normalized: a. Pearlitic steel; b. Bainitic steel; c. Martensitic steel; d. Austenitic steel. (3) Having no or partial phase transition
5. Classification by use
Engineering steel: a. ordinary carbon structural steel; B. Low alloy structural steel; C. Reinforcement steel.
Carburizing steel: a. Nitriding steel; b. Steel for surface hardening; c. Free cutting structural steel; d. Steel for cold plastic forming: including steel for cold stamping and steel for cold heading.
Carbon tool steel; a. Alloy tool steel; b. High speed tool steel.
Special performance steel: a. stainless acid resistant steel; b. Heat resistant steel: including oxidation resistant steel, heat strength steel and air valve steel; c. Electric heating alloy steel; d. Wear resistant steel; e. Low temperature steel; F. Electrical steel.
Steel for bridges, ships, boilers, pressure vessels, agricultural machinery, etc.
6. Comprehensive classification
High quality steel
(including high quality 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 applications.
Tool steel: (a) carbon tool steel; (b) Alloy tool steel; (c) High speed tool steel.
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 according to smelting method
Electric furnace steel: (a) electric furnace steel; (b) Electroslag furnace steel; (c) Induction furnace steel; (d) Vacuum consumable furnace steel; (e) Electron beam furnace steel.
nature
tensile strength
Elastic modulus
plasticity
Impact toughness, cold brittleness
hardness
Cold bending property
Weldability
heat treatment
Cold working and aging
Quality inspection
There are many items for quality inspection of steel including steel components, including tensile test, bending fatigue test, compression/bending test and corrosion resistance test. The quality performance of materials and related products can be mastered in real time during the R&D and production process, which can avoid quality returns and waste of raw materials.