Q355R连铸坯表面微裂纹研究  

Study on surface microcracks of Q355R continuous casting slab

作　　者：常卓 杨军[1] 徐李军[2] 仇圣桃[2] 时朋召 田玉石 CHANG Zhuo;YANG Jun;XU Lijun;QIU Shengtao;SHI Pengzhao;TIAN Yushi(School of Metallurgical Engineering,Xi′an University of Architecture and Technology,Xi′an 710055,Shaanxi,China;National Engineering Research Center of Continuous Casting Technology,Central Iron and Steel Research Institute,Beijing 100081,China)

机构地区：[1]西安建筑科技大学冶金工程学院,陕西西安710055 [2]钢铁研究总院连铸技术国家工程研究中心,北京100081

出　　处：《钢铁研究学报》2021年第12期1296-1306,共11页Journal of Iron and Steel Research

摘　　要：裂纹是影响连铸坯质量的主要缺陷,其成因和影响因素复杂众多。针对Q355R连铸坯表面微裂纹,在铸坯典型裂纹处采用金相观察、扫描电镜、能谱进行表征,进一步分析其形成机制,进而对连铸工艺进行优化改进。结果表明,铸坯表面的微小裂纹,其形貌不同于传统的网状星形裂纹和横裂纹,裂纹端主要为钝口且无延伸端,个别裂纹上端存在微裂纹细线,裂纹端呈"针"状且有延伸段。微裂纹主要成因是由结晶器卷渣、钢水二次氧化、钢水过热度大以及在连铸机弯曲和矫直区域外部应力共同作用所导致。通过对水口结构优化,改善结晶器流场,减弱结晶器卷渣,以及对连铸工艺优化,使铸坯表面微裂纹得到了有效控制。The main factor that affects the quality of continuous casting slab is crack, which has many causes and complex influencing factors. The microcracks on the surface of the Q355 R continuous casting slab, it is characterized by optical microscope, scanning electron microscopy, and energy dispersive spectrometer at the typical cracks of the cast slab. Through further analyzing the formation mechanism of crack, the continuous casting process was optimized and improved. The results showed that the morphology of the microcracks on the surface of the cast slab is different from the traditional reticulated star crack and transverse facial crack. The crack end is mainly blunt and has no extension end, besides, there are fine lines of microcracks at the upper end of the individual crack. The crack end is a "needle" shape and exists an extension section. The formation of microcracks is mainly caused by mold slag entrapment, molten steel reoxidation, high liquid steel superheat, and external stress in the bending and straightening area of the continuous casting machine. The microcracking on the slab surface has been effectively controlled, which by optimizing the nozzle structure, improving the mold flow field, weakening the mold slag entrapment, and optimizing the continuous casting process.

关 键 词：连铸坯 微裂纹 裂纹形貌 金相组织 

分 类 号：TG249.7[金属学及工艺—铸造] TG250.6