Effect of Vanadium and Niobium on the Microstructure of Carbide Reinforced Indefinite Chilled Cast Rolls

Abstract

In the present work, effects of elements vanadium and niobium on the microstructure of the conventional indefinite chilled rolls made by small vertical centrifugal caster were investigated, using optical microscopy, Scanning Electron Microscopy (SEM, Jeol 6400), Energy Dispersive X-ray Spectroscopy (EDXS, Cu-K radiation) to identify the type, morphology, and to measure the volume fraction and the distribution of carbides and graphites formed during solidification. Microstructural analysis indicates that, the amount of graphite is dramatically reduced by adding V element. The volume fraction of the square-like carbides NbC increases with the Nb content increasing. However, if Nb content is over a critical point, large amount of the square-like NbC carbide can be seriously segregated in the out part of the section.