MASTERING STEEL SLAB INTERNAL SOUNDNESS AND SURFACE QUALITY ISSUES THROUGH THERMOMECHANICAL MODELLING OF CONTINUOUS CASTING

摘要

High tensile strength steels are currently developed for automotive applications. These steels contain a large amount of alloying elements, which lead to both increased centreline segregation and internal cracking sensitivity. In addition, surface quality issues affect slabs of micro alloyed steel grades with ≈0.1% carbon content. The improvement of the product quality with the maximum productivity requires the implementation of operating means in the continuous casting machine to master both the slab internal soundness and surface quality. In order to define optimal process parameters like casting speed and cooling pattern, according to the steel grade properties and the casting machine characteristics, a two-dimensional and a three-dimensional finite-element macroscopic thermomechanical model of steel slab continuous casting has been developed at CEMEF. For the moment, the application of this modelling at ARCELOR RESEARCH has mainly been focused on the secondary cooling to simulate: 1. the slab bulging in order to be able to define soft reduction conditions to avoid centreline segregation 2. the slab surface thermomechanical behaviour close to the corners, to reduce the risks of transverse cracking.