摘要
在使用热轧GCr15圆钢斜轧生产轴承套圈用毛管过程中,发现部分钢管存在螺旋状内折缺陷,且缺陷在整根钢管上呈随机分布。借助低倍酸洗检验、金相检验、扫描电镜及能谱分析等试验方法对毛管内折缺陷进行了系统分析,结果在内折裂纹和附近基体上均发现了结晶器保护渣成分,两者微区能谱成分显示均含有结晶器保护渣最具特征的Na元素,同时夹渣中CaO/SiO_(2)≈1。利用排除法确定了管坯生产过程中结晶器液面波动引起的保护渣卷渣是造成钢管内折的主要原因,连铸过程工艺追踪发现第6流结晶器液面波动幅度最大,达12 mm,超出正常波动范围(±5 mm),持续时间40 min,执行了甩坯操作。同时对内折形成机理进行了分析。通过控制连铸关键工艺浸入式水口直径为32 mm,拉速1.0 m/min,连浇炉次钢水过热度10~30℃等工艺措施,结晶器液面长时间(≥10 min)剧烈波动(相对液面波动振幅>5 mm)发生时间占整个浇次总时间的百分比由最差时的15%下降至3%以下,提升了连铸坯内部质量,避免了毛管内折缺陷的发生。
In the process of producing capillary tubes for bearing rings by hot rolled GCr15 round steel diagonal rolling,it was found that some steel pipes had spiral internal folding defects,and the defects were randomly distributed on the whole steel pipe.The internal folding defects of capillary were systematically analyzed by means of low power pickling test,metallographic inspection,scanning electron microscopy and energy spectrum analysis,and the results were found in the internal fold crack and the nearby matrix,and the micro-energy spectrum components of both showed that they contained the most characteristic Na element of the crystallizer protective slag,and CaO/SiO 2≈1 in the slag inclusion.The protective slag roll slag caused by the liquid level fluctuation of the crystallizer in the continuous casting process during the production of the pipe blank was determined by the elimination method,and the continuous casting process traced and found that the liquid level fluctuation range of the 6th flow crystallizer was the largest,up to 12 mm,which exceeded the normal fluctuation range(±5 mm)and lasted for 40 min,and the billet dumping operation was performed.At the same time,the formation mechanism of internal folding was analyzed.By controlling the key process of continuous casting,such as the diameter of the immersion nozzle of 32 mm,the tensile speed of 1.0 m/min,and the superheat of the molten steel in the continuous casting furnace of 10~30℃,the percentage of the occurrence time of the liquid level of the crystallizer for a long time(≥10 min)of the sharp fluctuation(relative liquid level fluctuation amplitude>5 mm)in the total time of the entire casting time decreased from 15%at the worst time to less than 3%,which improved the internal quality of the continuous casting billet and avoided the occurrence of capillary internal folding defects.
作者
陈涛
靳国兵
窦文亚
郝志超
孙俊喜
Chen Tao;Jin Guobing;Dou Wenya;Hao Zhichao;Sun Junxi(Technical Center of HBIS Group Hansteel Company,Handan 056015,Hebei)
出处
《河北冶金》
2023年第9期58-62,共5页
Hebei Metallurgy
关键词
轴承套圈
GCr15钢管
内折
缺陷
保护渣
卷渣
bearing rings
GCr15 steel pipe
internal fold
flaw
protective slag
roll slag
