酒钢CSP薄板坯纵裂纹的形成机制

Form Mechanism of CSP Thin Slab Longitudinal Crack in JISCO

酒钢CSP连铸连轧生产线生产热轧卷板过程中,阶段性出现表面纵裂纹缺陷,导致大量废品。研究过程对缺陷在厚度规格、宽度规格的统计规律进行了分析,对成品板材缺陷与铸坯缺陷宏观形态与分布特征进行了对比,对成品板材裂纹缺陷进行了金相分析,并使用扫描电镜对缺陷进行了形貌与能谱分析。最终确定此种裂纹发源于结晶器弯月面处凝固前沿不均匀的热力学条件,在结晶器锥度不合适、二冷区冷却不均匀条件下进一步发展,导致铸坯表面裂纹达到足以产生成品表面裂纹的程度。按照分析结果,针对钢水成分、主要浇注工艺参数、保护渣、连铸设备等各个方面制定出控制措施,在实际应用中取得了显著效果。

Surface longitudinal cracks appear periodically in the production of hot-rolled coil of CSP continuous casting,resulting in a large number of wastes.The finished sheet defects with slab defects macro morphology and distribution characteristics were compared,the statistical rule of defects on thickness specification and width specification was analyzed,metallographic analysis was made on the finished sheet crack,and microscopy morphology and EDS analysis was made by scanning electron.Finally,it is determined that the thermodynamic conditions of such cracks are originated from the uneven solidification front of meniscus.It has further development on the condition of mold taper inappropriate and uneven cooling of the secondary cooling zone which lead to the slab surface cracks to the extent sufficient to produce a finished surface cracks.Control measures were made on the molten steel composition,main casting parameters,casting power can equipment and significant effects have already been achieved practically.