高拉速方坯内部裂纹产生原因分析

济钢一炼钢方坯铸机提高拉坯速度后出现了铸坯内部裂纹，分析其原因是二冷配水制度不合理以及钢水过热度高，为此在保证钢水流动性良好的条件下采用低过热度浇注工艺，同时采取中间包扩容，改进结晶器及二次冷却系统等措施，使铸坯鼓肚现象基本消除，方坯内部裂纹发生率由３０％降到２．５％。

Cause Analysis on Inner Crack of High Drawing Speed Billet

When continuous casting machine of billet increases the drawing speed in No.1 steelmaking plant of Jinan iron and steel group,the inner crack is appeared in billet. Throug analyzing,the producing causes of inner crack are unreasonable contributing water system at secondary cooling zone and high overheat of liquid steel.Because taking on some measures consisted of using of lower overheat pouring process of liquid steel under condition of insuring excellent flowability,expanding tundish volume,improving mould and secondary cooling system,etc,the drum phenomenon of billet can be basically eleminated,and the producing ratio of inner crack of billet is decreased from 30% to 2.5%.