VD冶炼管线钢纯净度的控制

CONTROL OF PURITY OF VD SMELTING PIPELINE STEEL

管线钢作为一种用途广泛的钢种,对性能以及夹杂物水平的要求较高。依托首钢京唐公司钢轧作业部中厚板产线X70管线钢生产工艺,分析了冶炼过程中夹杂物成分的变化规律,夹杂物数量、尺寸的变化以及夹杂物数量占比等。结果表明,LF进站到中间包浇注过程中,夹杂物类型由Al_(2)O_(3)基逐渐向CaO基转变,且夹杂物数量有所增加,夹杂物尺寸逐渐减小;指出Ca/S是引起夹杂物不合的主要原因。通过减少钙线用量、控制吹氩时间>10 min、新增开式冷却塔、严控钢水二次氧化、恒拉速操作等措施,夹杂物控制控制水平不断提升。

As a kind of widely used steel,pipeline steel requires high performance and inclusion level.Based on the production process of X70 pipeline steel for medium and heavy plate production line in Steel Rolling Department of Shougang Jingtang,the variation law of inclusion composition during smelting process is analyzed,the change of the amount and size of inclusion and the proportion of the amount of inclusion.The results show that the type of inclusions changes from Al_(2)O_(3) to CaO,the number of inclusions increases and the size of inclusions decreases during the pouring process from LF to tundish.It is pointed out that Ca/S is the main cause of inclusion incompatibility.By reducing the amount of calcium wire,controlling argon blowing time more than 10 min,adding a new open cooling tower,strictly controlling the secondary oxidation of molten steel and constant casting speed,the level of inclusion control has been improved continuously.