新型薄板坯连铸结晶器内腔形状设计

由于结晶器内坯壳应变至断裂主要是受应变速率的影响，应变速率的增大或突变均会使临界应变值降低，因此必须控制坯壳变形过程中的应变速率。基于此，根据薄板坯连铸结晶器内凝固坯壳收缩的特性，设计开发一种新型薄板坯连铸漏斗形结晶器。其特点是漏斗区曲线曲率连续变化，曲率变化率小且恒定，铸坯应变速率不突变，改变已知漏斗形结晶器内腔组合曲线的G1连续为G2连续。创建结晶器漏斗区横、纵向曲线的表达式，并根据坯壳凝固收缩特性和变形机理编程计算构造漏斗区曲面。建立新型漏斗形结晶器内铸坯的热力耦合有限元模型，分析计算宽面坯壳表面应力分布，并与进口技术进行对比。结果表明，结晶器坯壳表面应力水平下降20％，特别是在现有技术生产的铸坯易发生裂纹处，坯壳应力下降更加显著，应力下降达35％。因此该技术能够有效地减小铸坯裂纹形成机会，提高铸坯质量。

Design of Cavity Shape for a New Thin Slab Continuous Casting Mold

Because strain rate has an main influence on critical strain of shell in the mold, the increase or sudden change of strain rate makes critical strain decrease, the strain rate of shell must be controlled. Considering the shrinkage characteristic of solidified shell in the thin slab continuous casting mold, a new thin slab continuous casting funnel mold is developed. In the new mold, funnel curve curvature varies continuously, the curvature variation is small and constant, and the shell strain rate does not suddenly change. The funnel curve reaches G2 continuity. The expressions of horizontal and vertical curve in funnel area are given. Considering solidified shell shrinkage and deformation, the self-developed computation code is used to construct the funnel curved surface. The stress distribution of wide face shell is solved by a thermo-mechanical coupled model. Compared with import technology, the result indicates that the stress of wide face shell in mold decreases 20%, especially the stress decreases 35% at the area of cracking susceptibility. The possibility of cracking is reduced effectively and the quality of thin slab is improved in the new mold.