Second.the classification of steel for prefabricated steel structure
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
1) 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) structure steel:
A.machinofacture steel :
a)adjust for structural steel;
b)Surface induration structure steel:Including carburized steel, ammonia steel, surface hardened steel;
c) easy to cut structural steel;
d) cold plastic forming steel: including cold stamping steel, cold forging 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.
1) Nomal material:
A.carbon construction steel:
(b) Q215 (A, B);
(c) Q235 (A, B, C);
(d) Q255 (A, B);
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.
C.special performance steel:
(a)non-acid resistant 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.
c.electric furnace(Refining high quality steel):
(a)electric arc furnace steel;
(b) electroslag furnace steel;
(c) induction furnace steel;
(d) vacuum consumption furnace steel;
(e) electron beam furnace steel;
2) according to the degree of deoxidation and pouring system points:
a.boiled steel (incomplete degree of deoxidation);
b. semi-killed steel (deoxidation between the boiling steel and sedimentary steel);
c. sedative steel (more complete degree of deoxidation);
d. special sedative steel (the most complete degree of deoxidation, high quality steel).
8. according to the shape classification: divided into:
d. Metal products four categories.
Heavy rail: more than 30 kg per meter weight of the rail (including the crane rail);
Light rail: 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);
plank 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.