连铸方坯轻压下内裂纹形成研究

Research on formation of internal cracks by soft reduction in billet continuous casting

通过Abaqus/Explict建立方坯轻压下热力耦合模型,并通过凝固相变模型计算裂纹敏感性温度区间,研究内裂纹形成机理,得到了轻压下过程方坯温度分布、应力应变状态,分析了轻压下过程中脆性温度区内裂纹与等效塑性应变、最大主应力的关系。研究结果表明,脆性温度区内应变超过临界应变或存在拉应力时内裂纹开始萌生,脆性温度区拉应力是造成裂纹形成的最要因素,分析结果为优化轻压下工艺提供参考,可以优化铸坯轻压下的变形分布,提高铸坯内部质量。

To investigate the formation of internal cracks in steel billets during soft reduction with liquid core, fully coupled thermo-mechanical finite element models were developed by Abaqus/Explict, and sensitive temperature range of internal crack was calcu- lated by solidification phase transition model. With the finite element models, the tem- perature distribution, the stress and strain states in the billet were calculated. The relation between internal cracks and equivalent plastic strain, as well as maximal principal stress was analyzed. The results indicate that internal cracks will be initiated when the accumulated strain exceeds the critical strain or the applied tensile stress exceeds the critical fracture stress during solidification. The results can provide references for the optimization of soft reduction in strand deformation distribution and improving the internal quality of the strand.