Numerical Modeling Of Solidified Microstructure In Vertical Semi-continuous Casting With A Large Cross-section

The production of casting billets with a extra large cross-section is still a difficultissue in the metallurgical industry. Numerical modeling is a necessary method toanalyze the solidification microstructure of semi-continuous casting process and toinvestigate the influence of different process conditions on solidification structure, andthus is efficient tool to develop a1600mm×500mm vertical large section of semicontinuous caster.In this paper, according to the characteristics of vertical semi-continuous castingand the complex process of the liquid steel solidification, a CA-FE model wasestablished by coupling the finite element and cellular automaton method. Thesemi-continuous casting process with a cross-sectional dimension1600mm×500mmis studied, a physical model of the casting slab is established based on finite elementsoftware ProCAST. The vertical semi-continuous casting process, solidification processand microstructure are simulated under different conditions and parameters. The effectsof different superheat, casting speed, secondary cooling intensity on the solidificationmicrostructure are analyzed.The results showed that: With the CA-FE model coupling macro and micro scale,the temperature field, solidification process and microstructure of a verticalsemi-continuous slab with large cross section can be properly simulated. With theincrease of superheat, the average grain size and equiaxed grain proportion increases.Thus, a lower superheat for casting should be chosen. The effect of casting speed onsolidification structure is also previous. Faster casting speed can produce a billet withdecreased the average grain size and equiaxed grain proportion. the secondary coolingrate is another important factors which influences the microstructure of the billets. witha stronger secondary cooling, a microstructure with smaller size grains and equiaxedgrain proportion can be obtained.