连铸大方坯气瓶钢白点缺陷的防止

Prevention of flake defects in gas cylinder steel produced by continuous bloom casting

介绍电炉—大方坯连铸生产气瓶钢防止白点缺陷的改进措施。连铸大方坯轧制后的气瓶钢坯上经常发现轻微白点缺陷,在连铸中间包的开浇炉上更为明显。白点缺陷存在安全隐患,是气瓶钢中不允许存在的缺陷,为此加强对炼钢原辅材的防潮、VD真空过程以及中间包烘烤时间的管理,同时通过不同缓冷方式的试验,确定最合适的缓冷工艺,有效避免了轧制后钢坯白点现象的发生。在低倍组织检验时这种细小白点缺陷容易漏判,采用超声波探伤检查,对防止白点误判非常重要。

This paper introduces the measures to prevent flake defects in gas cylinder steel produced by the process of electric arc furnace-continuous casting. After being rolled, the gas cylinder steel produced by continuous bloom casting often have small flake defects. In particular, these defects are more obvious in the steel of the first heat during continuous casting. As flakes will cause safety problems, they are not allowed to exist in gas cylinder steel. In order to prevent flake defects, measures have been taken to protect raw material from moisture, and to strengthen the management of VD vacuum degree and tundish baking time. In addition, the most appropriate slow cooling process have been determined based on experiments. Good results have been achieved by adopting these measures. However, tiny flake defects are easily missed in macrostrueture inspection. Therefore, ultrasonic testing is very important for the detection of flakes.