More economical heating of continuous-cast 60C2XA steel billet in continuous furnaces

Abstract

Scale formation and the kinetics of high-temperature oxidation and decarburization of 60C2XA steel are investigated in the laboratory. Oxidation intensifies sharply at metal temperatures around 1000°C. The first liquid sections appear in the scale at 1270–1280°C, while melting of the scale accompanied by its escape from the metal surface begins at 1300°C. Decarburization of the steel is most intense at 950–1100°C; at 1175°C and above, a mixed zone consisting of ferrite and oxides (thickness 0.030–0.045 mm) is seen on the metal surface, hindering scale removal. Empirical formulas permit prediction of the metal losses on heating in the rolling line. For practical use, a heating protocol ensuring reduced metal loss is developed for continuous-cast billet in stepping-hearth continuous furnaces, on the basis of a mathematical model.