Niobium in Si-Mn rail steel

The research center of the Brazilian National Steel Co. has been conducting studies on Nb-bearing Si--Mn rail steel as an alternative way to improve railway service performance. Strengthening mechanisms through microalloying additions of Nb in Si--Mn rail steel are reviewed and metallographic, mechanical and weldability characteristics are presented. The results from laboratory tests (fracture mechanics, wear resistance and rolling contact fatigue) and from in-service tests carried out on two Brazilian heavy haul railways are analyzed. (AU)