The influence of common impurities on the properties of steel

The influence of common impurities on the properties of steel

1, sulfur: sulfur is a harmful element in steel, often in the form of FeS, FeS and Fe to form a low melting point eutectic, melting point is 985℃, distributed in the grain boundary, when the steel in (1000 ~ 1200) ℃ for pressure processing, eutectic melting, making the steel brittle, this phenomenon is called hot brittleness.

To avoid hot embrittlement, the sulfur content in steel must be strictly controlled, usually to S<0.05%.

2, phosphorus: phosphorus is also a harmful element in steel, it makes steel brittle at low temperature, this phenomenon is called cold brittleness, therefore, the phosphorus content in steel should be strictly controlled, usually should be P<0.045%.

3, manganese: manganese is a beneficial element in steel, steel is used to deoxidize ferromanganese iron and residual in steel, manganese has a good deoxidization ability, but also can form MnS with sulfur, thereby eliminating the harmful effect of sulfur.

Manganese as an impurity should generally not exceed 0.8%.

4, hydrogen: steel hydrogen can cause hydrogen embrittlement, white spots and other defects, is a harmful element.

5, silicon: silicon is also a beneficial element in steel, but also as a deoxidizer into steel, silicon deoxidization capacity is stronger than manganese, but also can improve the strength and quality of steel, silicon as impurities should not exceed 0.4%.