Influence of the constituents on Steel

The properties of steel depends on the carbon content and to a large extent upon silicon, manganese, sulphur and phosphorus.

Carbon: It increase strength, hardness, lowers ductility and impact strength

Silicon: It acts as a very good deoxidizer and removes the gases and oxides, prevents blowholes and makes steel harder and tougher

Manganese: It serves as deoxidizer and purifying agent. It combines with sulphur and decreases the harmful effect of this element remaining in the steel. It makes metal ductile and of good bending qualities.

Sulphur: It occurs in steel as iron sulphide or as manganese sulphide. Iron sulphide, because of its low melting point, produces red-shortness. Manganese sulphide is less objectionable in steel than iron sulphide.

Phosphorus: It imparts cold-shortness, i.e., high brittleness at normal and especially at low temperatures. It increase tensile strength but also reduces the impact strength and the ductility.