We begin with a discussion of the influence of alloying elements normally used in the manufacture of construction-grade steels. The following distinctions are commonly used in the steelmaking process:

  • Primary alloying elements (C, Mn, Si): These elements are added to refined molten metal in order to produce various grades of steel, which have specific metallurgical properties that often can be enhanced by heat treatment.
  • Secondary alloying elements (Cu, Ni, Cr, Mo, Al, V, Nb, B, Co and W): These elements are normally added to the steel along with the primary elements to further enhance properties and performance.
  • Residual elements (Cu, Ni, Cr and Mo; may include Co and W): A residual element is one present in the molten bath for which no minimum content is specified for the grade to be produced. A maximum content may or may not be required by the grade specification. Whether covered by grade specifications or not, residuals may have a positive or negative effect on steel properties.
  • Tramp elements (primarily – but not limited to – S, P, Pb, Sn, Sb, Zn, Cd and Hg): “Tramp elements” is a term commonly applied to certain elements that serve no useful purpose in the steelmaking process. Even in minute amounts they almost always have an (adverse) effect on steel properties.