连铸圆管坯穿管内鼓包原因分析与控制

Cause Analysis and Control of Inner Pipe Bulge Forming during Round Billet Piercing

针对由连铸坯生产N80级石油套管时钢管内表面出现的鼓包缺陷问题,采用金相显微镜和扫描电镜对其进行了研究分析,发现鼓包缺陷内部存在聚集的大型夹杂物。鼓包缺陷的形成是在穿管深加工过程中管壁不断减薄,夹杂物逐渐外露,内表皮外翻所致。鼓包处的夹杂物是以铝酸钙组分为主,还存在少量结晶器保护渣和水口侵蚀后的剥落物。聚集的大型夹杂物与钢水的纯净度、下水口侵蚀和结晶器液面波动有关。

Study and Analysis were conducted on bulge defects on the inner surface of N80 oil casing produced by continuous cast round billet with metallographie microscope and scanning electron microscope. Big inclusions were found to aggregate inside the bulge. With pipe wall was increasingly thinned during the deep processing of piercing, inclusions came to expose and inner surface turned out, which caused the formation of bulging. The inclusions at bulge were dominated by calcium aluminate and included small quantities of mould powder and spall due to nozzle erosion as well. Big inclusion aggregate was related to steel cleanliness, lower nozzle erosion and mould level fluctuation.