Low-alloy Structural Steel

Low-alloy structural steel
(Also known as ordinary low-alloy steel, HSLA)
1 Uses of Low-alloy structural steel
Mainly for the manufacture of bridges, ships, vehicles, boilers, pressure vessels,oil pipelines,large steel structure and so on.
2 Performance Requirements of Low-alloy structural steel
(1) High strength:Usually the yield strength is above 300MPa.
(2) High Resilience: requires an elongation of 15% to 20%, impact toughness at room temperature greater than 600kJ / m ~ 800kJ / m. For large welded components,it requires a higher fracture toughness.
(3) good weldability and cold forming properties.
(4) low cold brittle transition temperature.
(5) good corrosion resistance.
3 Ingredient of Low-alloy structural steel
(1) carbon: cause of the requirments of the toughness, weldability and cold formability,a carbon content can not exceeding 0.20%.
(2) adding a manganese-based alloy elements.
(3) by adding niobium,titanium or vanadium add elements: a small amount of niobium,titanium or vanadium in the steel to form fine carbides or carbonitrides are conducive to obtaining fine ferrite grains and improving the strength and toughness of steel .
In addition,small amount of copper (≤ 0.4%) and phosphorus (about 0.1%), can increase the corrosion resistance.Add a small amount of rare earth elements,can desulfurization,degassing,the steel purify and improve toughness and process performance.

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