Manganese
About 0.25% to 0.80%. Solid solution strengthening; removal of FeO, reducing the brittleness of steel; and synthesis of MnS with sulfur, can reduce the harmful effects of sulfur. Helpful.
Silicon
About 0.10% ~ 0.40%, solid solution strengthening; In addition to the adverse effects of FeO on steel quality, beneficial.
Sulfur
FeS and Fe form a low-melting point eutectic (melting point of 985°C), which causes the steel to become brittle and crack when hot-worked at 1000 to 1250°C. harmful.
Phosphorus
Strength and hardness increase, but the plasticity and toughness decrease, "cold and brittle." harmful.
