ABSTRACT
The oxidation of low alloy steels during the hot rolling process is one of the serious constraints that often prevent the use of high temperatures in order to fully dissolve micro-alloying element phases (such as niobium carbides) or to obtain higher production rates associated with lower rolling forces. One of the important species in the oxidation process is silicon which is often associated with internal oxidation and the formation of a silicate layer on the metal/scale interface during high temperature exposure.
The development of internal oxides with silicon, the formation of a sub-scale, and precipitation reactions involving silicates and iron oxides within the scale are illustrated. Special attention is given to the various iron silicate species that can develop in the scale on slabs of BS 4360 Gr.50E steel during exposure in the reheating cycle prior to hot rolling. Examples of scale morphologies are shown and the influence of silicates on descaling during hot rolling is indicated.
