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.