连铸凝固末端压下过程裂纹萌生扩展风险预测

Risk prediction of crack formation and propagation in solidification end reduction process of continuous casting slab

随着连铸断面的增宽加厚,浇铸钢种中碳及合金占比的显著增加,以及铸坯质量要求愈发严苛,大幅增加压下量、延长压下区间已成为凝固末端压下工艺发展的普遍共识,生产者们也愈加担心诱发压下裂纹的风险。针对微合金钢宽厚板坯在凝固末端压下过程的变形特点,设计了中间裂纹萌生与角部裂纹扩展的临界应变测定方法。采用三维热/力耦合有限元仿真模型,分析了宽厚板坯凝固末端压下过程铸坯凝固与变形规律,结合临界应变,建立了裂纹萌生扩展风险的预测模型,并分析了不同压下方案下的裂纹风险,为压下工艺设计提供了定量数据支撑。

It was gradually recognized that the reduction amount increase and reduction zone extension are necessary for improving center segregation and porosity of large section continuous casting slab and bloom, and the risk of crack formation and propagation would be increased inevitably. Combing with the mechanism of internal crack formation and transverse corner crack propagation during solidification end reduction process, the critical strain determination method of two kinds of cracks was designed. The solidification and deformation behavior of wide-thick continuous casting slab was analyzed using finite element method. The risk prediction model of these two typical cracks was presented, and the crack risks with different solidification end reduction conditions were simulated for quantitatively designing of reduction amount and zone parameters.