Manganese
Manganese slightly increases the strength of ferrite, and also increases the hardness penetration of steel.
Chromium
Chromium (Cr) has a tendency to increase hardness penetration. Chromium can also increase the toughness and wear resistance of steel. Probably one of the most well known effects of chromium on steel is the tendency to resist staining and corrosion. Steels with 12% or more chromium are referred to as stainless steels.
Silicon
Silicon is used as a deoxidizer in the manufacture of steel. It slightly increases the strength of ferrite, and when used in conjunction with other alloys can help increase the toughness and hardness penetration of steel.
