Unalloyed Steel

Unalloyed steel refers to iron-carbon alloys dominated by iron, with a mass fraction of carbon generally less than 2%, and containing a small number of other elements.

1.Classification by the mass fraction of carbon in steel:

low carbon steel (Wc<0.25%), medium carbon steel (0.25%≤Wc≤0.60%), high carbon steel (Wc> 0.60%)

2.Classification by use of steel:

Carbon structural steel is mainly used to make mechanical parts, engineering structural parts, generally belong to low and medium carbon steel.

Carbon tool steel is mainly used to make cutting tools, measuring tools and molds. Generally high carbon steel.

3. Classification by main quality grade of steel：

Ordinary quality non-alloy steel (Ws≥0.045%,Wp≥0.045%) refers to the steel that does not require special quality control requirements in the production process. It mainly includes: general purpose carbon structural steel, carbon reinforcement steel, general carbon steel for railway, etc.

High-quality non-alloyed steel (sulfur and phosphorus content less than ordinary quality carbon steel), high-quality carbon steel refers to carbon steel other than ordinary quality carbon steel and special quality carbon steel, which requires special quality control (such as controlling grain size, reducing sulfur, phosphorus content, improving surface quality, etc.) in the production process to achieve special quality requirements (Compared with ordinary quality carbon steel, it has good brittle fracture resistance and cold formability etc.)It mainly includes: high-quality carbon steel for mechanical structure, carbon steel for engineering structure, low carbon structural steel for stamping sheet, carbon steel for welding rod, non-alloy free cutting structural steel, high-quality cast carbon steel and so on.

Special quality non-alloy steel (Ws< 0.020%, Wp< 0.020%), special quality carbon steel refers to carbon steel that requires particularly strict control of quality and performance (such as control of hardenability and purity) during the production process. Mainly include: to ensure the hardenability of non-alloy steel (carbon steel), railway special carbon steel, aviation, weapons and other special carbon steel, carbon steel for nuclear energy, special electrode steel, carbon spring steel, carbon tool steel and special free cutting steel.