包晶钢板坯尾坯偏角部裂纹产生机制及控制措施  

Mechanism and control measures of tail surface cracks near corners of peritectic steel slab castings

作　　者：董延楠 白云 沈毓 王鹏 陈斌 王璞 DONG Yannan;BAI Yun;SHEN Yu;WANG Peng;CHEN Bin;VWANG Pu(School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing,Beijing 100083,China;Jiangyin Xingcheng Special Steel Works Co.,Ltd.,Jiangyin 214429,Jiangsu,China)

机构地区：[1]北京科技大学冶金与生态工程学院,北京100083 [2]江阴兴澄特种钢铁有限公司,江苏江阴214429

出　　处：《钢铁研究学报》2024年第6期736-742,共7页Journal of Iron and Steel Research

基　　金：国家自然科学基金资助项目(U1860111)。

摘　　要：板坯尾坯浇铸属于非稳态工况,表面裂纹发生率较高,严重影响浇次钢水收得率。对某包晶钢板坯尾坯表层裂纹附近组织形貌进行分析,探究了其偏角部横裂纹特征、产生机制及控制措施。结果表明:尾坯表层室温组织为铁素体和珠光体且枝晶形貌明显。铸机拉尾坯工艺下,板坯出结晶器后角部经历了较强冷却→角部温度进入铁素体温区→回温→角部重新奥氏体化的过程。在该过程最低温度附近,尾坯角部落入第三脆性区,从而在后续弯曲变形下发生外弧表面开裂。此类尾坯角部横裂纹发生的关键在于铸坯角部在出结晶器后的冷却过强,其控制措施应考虑降低出结晶器后板坯角部的冷却强度,缩短尾坯浇铸时间;同时应关注板坯角部的冷却水覆盖范围,更换断面后应适时调整喷嘴位置,并注意保障设备对弧精度,以降低板坯弯曲应变。The tail strand casting of the slab is an unsteady-state working condition with a relatively higher surface crack occurrence,which significantly impacts molten steel yield during a sequence casting.The microstructure morphology near the surface cracks of the tail strand of a peritectic steel slab was analyzed,and the characteristics,formation mechanism and control methods of the corner transverse cracks were explored.The results show that the room temperature structure of the tail strand surface is ferrite and pearlite with obvious dendrite morphology.Under the tail strand casting process,the corners of the slab after exiting the mold have experienced a process of strong cooling-→the corner temperature enters the ferrite temperature zone-temperature reheating→the corner structure is austenitized.Near the lowest temperature in this process,the corner of the tail strand is in the third brittle zone,causing fixed-side surface cracking under subsequent bending deformation.The key to the occurrence of such transverse cracks at the corners of the slab is that the corners of the slab are cooled too hard after exiting the mold.The control measures should consider reducing the cooling intensity of the corners of the slab after exiting the mold and shortening the casting time of the tail strand;Additionally,attention should be paid to the coverage of cooling water at the corners of the slab.After replacing the section,the position of the nozzle should be adjusted on time,and attention should be given to ensuring the alignment accuracy of the equipment to reduce the bending strain of the slab.

关 键 词：板坯 尾坯偏角部横裂纹 双相变 枝晶形貌 冷却强度 

分 类 号：TG142.1[一般工业技术—材料科学与工程]