板坯连铸过程热收缩变形行为研究

Investigation on thermal shrinkage deformation of the continuously cast slab

连铸过程铸坯已凝固坯壳因冷却降温发生热收缩变形,该变形是制定连铸机基础收缩辊缝的重要依据。以板坯连铸过程为对象,建立了三维热-力耦合有限元模型,揭示了板坯连铸过程已凝固坯壳沿厚度方向热收缩变形规律。结果表明,浇铸过程中坯壳热收缩变形不断增大,在凝固终点位置热收缩出现短时加速增大趋势,铸机末端位置坯壳宽向中心位置热收缩约8 mm;板坯宽向不同位置热收缩变形存在较明显差异,由宽向中心至铸坯角部方向,已凝固坯壳厚度方向热收缩变形呈先减小后增大趋势。随着拉速增加,相同铸流位置热收缩变形减小,拉速增加0.1 m/min,铸机末端位置的坯壳宽向中心与宽向1/8位置热收缩减小约1.2 mm。研究结果为优化铸机基础收缩辊缝,改善因不合理基础辊缝导致的铸坯内部质量问题提供了数据支撑。

In the continuous casting process,thermal shrinkage deformation of the solidified shell occurs due to the temperature decrease during the cooling process,and this thermal shrinkage deformation is the important basis for designing basic shrinkage gap of the continuous casting machine.In the present work,a 3D thermal-mechanical coupling model was developed,and the thermal shrinkage deformation of the continuous casting slab was investigated.The results indicate that the thermal shrinkage deformation continuously increased during the continuous casting process and a rapidly increasing trend was observed at the solidification end of the strand.The total shrinkage of the wide surface center was~8 mm at the exit of the continuous casting machine.The difference of the thermal shrinkage deformation along the slab width direction was obvious,and the shrinkage deformation showed a decreasing trend first and then an increasing trend from the slab surface center to its corner.The thermal shrinkage at the same strand position decreased with increasing the casting speed,and the total thermal shrinkage of the wide surface center and 1/8 width decreased~1.2 mm with increasing the casting speed by 0.1 m/min.The present work provided data support for optimizing the basic shrinkage gap of the continuous casting machine and thus alleviating the internal quality of the continuous casting steel.