Sulfur (S): in pig iron is a harmful element, it promotes the combination of iron and carbon, make iron hard and brittle, and iron and iron chemical synthesis of low melting point of iron sulfide, so that pig iron produces thermal brittleness and reduce the fluidity of the liquid iron, Gu high sulfur pig iron is not suitable for casting fine parts. The sulfur content of cast pig iron shall not exceed 0.06% at most (except wheel pig iron).