摘要
针对∠200mm×24mm的Q420B热轧角钢酸洗后发现上表面有凹坑及结疤缺陷,采用化学成分分析、夹杂物分析、金相组织检验及电镜分析手段,对Q420B热轧角钢表面凹坑及结疤的产生原因进行了分析。分析结果表明:Q420B热轧角钢表面凹坑是由结晶器保护渣卷入钢液造成的表层卷渣,在轧制过程中,卷入的保护渣与基体变形不一致,逐渐在基体中形成分层,轧制后期保护渣层逐渐露出带材表面,脱落后形成凹坑缺陷;结疤缺陷是由于钢坏出炉温度过高导致一次氧化皮难以剥离,因除鳞不彻底,会残留一定数量的FeO,氧化铁皮材质硬而脆,塑性较差,无法与基体同步延伸,故经轧制后,铁皮呈颗块状结疤。提出了防止类似缺陷产生的措施,降低加热温度缩短保温时间,选用合适保护渣,降低水口浸入深度,改善了表面质量。
For∠200mm×24mm Q420Bhot-rolled angle steel,pits and scabs are found on the upper surface after pickling.The causes of pits and scabs on the surface of Q420Bhot-rolled angle steel were analyzed by means of composition analysis,metallographic observation,scanning electron microscope and X-ray energy spectrum analysis.The analysis results show that the surface pits of Q420Bhot rolled angle steel are caused by the inclusion of mold flux into molten steel.During the rolling process,the inclusion of mold flux is inconsistent with the deformation of the substrate,and gradually forms delamination in the substrate.In the later rolling period,the protective flux layer gradually exposes the strip surface,and then forms pit defects after falling off;The scar defect is that the primary oxide skin is difficult to peel off due to the high temperature of the steel out of the furnace.Due to incomplete descaling,a certain amount of FeO will remain.The iron oxide skin is hard and brittle,with poor plasticity,and cannot extend synchronously with the matrix.Therefore,after rolling,the iron skin is scabbed in blocks.Measures to prevent similar defects are put forward,such as reducing Si content,heating temperature and holding time,selecting appropriate protective slag and reducing the immersion depth of nozzle.
作者
田秀刚
张春花
TIAN Xiugang;ZHANG Chunhua(Technical Center of Tangshan Iron and Steel Group Co.,Ltd.,Tangshan 063000,Hebei,China)
出处
《四川冶金》
CAS
2022年第5期40-45,共6页
Sichuan Metallurgy
