Q355B钢板表面星裂缺陷的研究与控制  

Study and control of surface star cracks on Q355B steel plates

作　　者：王龙飞 WANG Long-fei(Steelmaking Plant,Fujian Sangang Minguang Co.,Ltd.,Sanming 365000,Fujian,China)

机构地区：[1]福建三钢闽光股份有限公司炼钢厂,福建三明365000

出　　处：《连铸》2022年第5期82-87,107,共7页Continuous Casting

摘　　要：为解决Q355B钢板材表面星状裂纹问题,采用热力学计算、金相分析、修磨、抛丸、酸洗、低倍分析、扫描电镜及能谱分析等方式对表面星状裂纹产生的原因进行了系统研究。研究结果认为,Q355B钢板表面裂纹处未发现脱碳层、氧化原点、第二相粒子、夹杂物和铜元素,说明裂纹不是源于铸坯缺陷。对铸坯分别进行热装和冷装发现冷装铸坯生产的钢板裂纹比例较低,结合两相区分析表明星状裂纹产生主要与铸坯在Ar_(3)~Ar_(1)两相区767~677℃内进行热装有关。通过自主设计喷淋装置,控制铸坯喷淋前温度在790℃以上,在入加热炉前对铸坯进行喷淋冷却至510℃以下从而使入炉温度低于635℃,Q355B钢热装星裂由攻关前的0.99%降至2021年攻关后的0.07%。In order to eliminate the surface star cracks of hot rolled Q355 B steel plates,a series of methods including thermodynamic calculation,metallographic examination,grinding,shot blasting,acid pickling,macroscopic evaluation,SEM and EDS analysis were conducted to probe into the reasons.The results showed there is no finding of decarburized layer,oxidation origin,the secondary phase particle,inclusion and copper in the cracks,which indicated the occurrence of surface star cracks is not from slab defect.The low cracking ratio of steel plate produced by cold charging and analysis of two-phase domain demonstrated the occurrence of surface star cracks is mainly caused by hot charging of slabs in the two-phase domain between 767℃and 677℃.Through independent design and application of spraying device,and meanwhile controlling the temperature more than 790℃before entering spraying zone and then less than 510℃when leaving spraying zone,the slab surface temperature before entering the heating furnace was decreased to be less than 635℃.Eventually,the star crack ratio decreased from 0.99%before technology improvement to 0.07%at 2021.

关 键 词：Q355B钢板 表面星状裂纹 两相区 热装 喷淋 

分 类 号：TF777[冶金工程—钢铁冶金]