What is carbon structural steel and high quality alloy steel

Carbon structural steel, originally known as ordinary carbon structural steel, refers to the kind of steel which is mainly used in construction and engineering structure, without alloy elements specially added. In various kinds of steel, the output of carbon structural steel is large, the use is the most extensive, and the price is low. The carbon structural steel is often rolled into various steel bars (round steel, square steel, flat steel, hexagonal angle steel, handle angle steel, etc.), section steel (I-beam, angle steel, channel steel, L-shaped steel, etc.), profiled section steel and steel plates. The carbon structural steel is mainly used in buildings and engineering structures such as workshops, bridges, ships, etc. Generally, heat treatment is not required for carbon structural steel.

High quality alloy steel is made by adding one or several alloy elements (the total mass fraction is less than 5%) on the basis of high-quality carbon structural steel. The properties of different alloy elements are different with different contents. High quality alloy steel is mainly used to manufacture various parts with large size and complex shape, and it is difficult to meet the performance requirements with high-quality carbon steel. High strength and toughness can be obtained by proper heat treatment.