Question: what are the chemical components of structural steel?
Answer: Carbon – C. Carbon is added to iron to make steel. ... 
Silicon – Si. Silicon is added to carbon steels to help deoxidise, or kill, them. ... 
Manganese – Mn. ... 
Sulphur – S. ... 
Nitrogen – N. ... 
Niobium – Nb. ... 
Vanadium – V. ... 
Titanium – Ti.