冷轧双相钢DP590的连铸坯角部横裂纹研究  

Study on corner cross crack of continuous casting slab of DP590 cold rolled duplex steel

作　　者：李哲 李岩杰 田伟 杨杰 张大勇 杨晓江 LI Zhe;LI Yanjie;TIAN Wei;YANG Jie;ZHANG Dayong;YANG Xiaojiang(Tangsteel Company,HBIS Group,Tangshan 063000,China)

机构地区：[1]河钢集团唐钢公司,河北唐山063000

出　　处：《炼钢》2024年第5期81-88,共8页Steelmaking

摘　　要：冷轧双相钢DP590连铸坯角部横裂纹给冷轧产品的质量带来很大困扰,导致其后续连退产品边部出现夹渣、翘皮或裂纹等缺陷。通过对连铸坯角部横裂纹部位进行观察,发现角部横裂纹发生在连铸坯的振谷部位,横裂纹向铸坯宽面和窄面有一定的延伸,发生横裂纹的振谷通常是不规则振痕,其形貌带有横向的凹陷特征。通过连铸坯的枝晶侵蚀试验发现,连铸坯发生角部横裂纹的部位,二次枝晶间距大,裂纹处的连铸坯表面冷却速率显著低于正常的连铸坯表面,这说明连铸坯坯壳冷却均匀性需要改善。并且裂纹附近有明显异常粗大的枝晶间距,通过电子探针检测发现这些异常粗大枝晶间存在硫、锰的富集现象,说明这是凝固过程中枝晶间发生断裂,富集锰硫溶质的钢液补充形成的。结合浇铸的结晶器热电偶测量温度趋势,判断该型保护渣控制传热能力以及渣膜的稳定性不足。通过优化保护渣和提高铸坯拉速,消除了连铸坯凹陷和角部横裂纹。The transverse corner crack of DP590 steel slab brings great trouble to the quality of cold-rolled products,leading to the defects of slag inclusion,surface warping or crack on the edge of the subsequent continuous annealing products.The transverse cracks in the corner of slab were observed,and it was found that the transverse cracks occurred in the vibration valley of slab,and the transverse cracks extended to a certain extent to the wide and narrow faces of the slab.The vibration valley where the transverse cracks occurred was usually an irregular vibration mark with transverse depression.The dendrite erosion test of slab shows that the distance between secondary dendrites is large and the surface cooling rate of slab at the corner transverse crack is significantly lower than that of normal surface.These images show that the cooling uniformity of slab shell needs to be improved.Moreover,there was obviously abnormally thick dendrite spacing near the crack,and the accumulation of sulfur and manganese between dendrites of abnormal wide gaps was found by electron probe detection,indicating that the dendrite fracture occurred during the solidification process and the enrichment of manganese sulfur solute steel was formed.Combined with the mold temperature trend,it is concluded that the heat transfer control ability of the slag and the stability of the slag film are insufficient,which needs to be further improved and optimized.By optimizing the protection slag and increasing the casting speed,transverse depression and transverse corner cracks of the billet were eliminated.

关 键 词：角部横裂纹 二次枝晶 连铸坯 横向凹陷 DP590钢 

分 类 号：TF777.1[冶金工程—钢铁冶金]