Sulfur

It is not a desirable element in steel since it interferes with hot rolling and forging resulting in hot shortness or hot embitterment. On the other hand, S is helpful in enhancing free cutting nature. Sup to 0.33% is added in, free cutting steel. If steel is not free cutting such S is restricted to 0.05% in open hearth or converter steel and to 0.025% in electric furnace steel.

Phosphorous

It produces cold shortness, which reduces impact strength at low temperature. Hence its %age is generally restricted to level of S. This is helpful in free cutting steels and is added up to 0.12%. This also enhances resistance to corrosion.