Q345B thick walled steel pipe
Q345B thick-walled steel pipe
1, the steel quality classification
(1) ordinary steel (P ≤ 0.045%, S ≤ 0.050%)
(2) excellent steel steel (P, S ≤ 0.035%)
(3) High quality steel (P ≤ 0.035%, S ≤ 0.030%)
2, according to the chemical composition of classification
(1) carbon steel: steel of a low carbon steel (C ≤ 0.25%); b. Medium carbon steel (C ≤ 0.25 to 0.60%); c of high-carbon steel (C ≤ 0.60%).
(2) alloy: a low alloy steel (alloy elements the total content of ≤ 5%); b medium alloy steel (alloying elements the total content of> 5 to 10%); c of high-alloy steel (the total content of alloying elements> 10 %).
3, steel forming methods:
(1) forged steel; (2) Steel; (3) hot-rolled steel; (4) cold-drawn steel.
4, the steel microstructure Category
(1) annealed state: a. Alkylene eutectoid steel (ferrite + pearlite); b a eutectoid steel (pearlite); c. Over total steel eutectoid steel (pearlite + cementite); d. ledeburite (pearlite + cementite).
(2) normalizing the state: a pearlitic steel; b bainitic steel; c martensitic steel; d. Austenitic steels.
(3) steel no phase change or phase transition
5, use classification
(1) the construction and engineering steel: a plain carbon structural steel; b low-alloy structural steels; c reinforced steel.
(2) steel structural steel
a. the mechanical manufacturing steel: (a) quenched and tempered structural steel; (b) surface hardened structural steel: including the carburizing steel seepage ammonia steel surface hardening steel; (c)-cutting structural steel; (d) cold plastic forming of steel: 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 resistant stainless steel; b heat-resistant steel: including antioxidant steel, heat resistant steel, valve steel; c. Electrothermal alloy steel; d. Wear-resistant steel; e cryogenic steel ; f electrical steel.
(5) professional steel - such as bridge steel, shipbuilding, steel, boiler steel, pressure vessel steel, agricultural steel.
6, the overall classification
(1) ordinary steel
a. carbon structural steel: (a) Q195; (b) Q215 (A, B); (c) Q235 (A, B, C); (e) Q275 (d) Q255 (A, B);
low alloy structural steel
c. specific uses ordinary structural steel
(2) high-quality steel (including high-quality steel)
a steel structural steel: (a) high-quality carbon structural steel; (b) alloy structural steel; (c) spring steel; (d) cutting steel; (e) bearing steel; (f) quality structural steel for a particular purpose.
tool steel: (a) carbon tool steel; (b) alloy tool steel; (c) high-speed tool steel.
c. a special performance steel: (a) acid-resistant stainless steel; (b) heat-resistant steel; (c) electric alloy steel; (d) electrical steel; (e) high manganese wear-resistant steel.
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