拉速变化对IF钢铸坯非金属夹杂物含量的影响

Influence of casting speed variation on non-metallic inclusions in IF steel slabs

采用原位统计分布分析仪(OPA)对IF钢连铸过程拉速变动对铸坯表层试样非金属夹杂物含量的影响进行了研究,发现在由较高拉速(1.4m/min)向低拉速(0.6m/min)变动时,对结晶器保护渣卷入的影响主要发生在降速初期,而随后的降速和低拉速下停止降速对铸坯表层试样夹杂物含量影响不大。当由较低拉速(0.6m/min)向高拉速(1.4m/min)变动时,对保护渣卷渣的影响主要发生在提升到高拉速后停止升速阶段,而低拉速时启动升速和随后均匀升速对铸坯夹杂物含量的影响不大。研究中还发现在较高拉速下(1.4m/min)即使较少量地变速,也会造成铸坯表层夹杂物含量的显著增加,因此在较高拉速时应避免对拉速进行变动或尽量采用低的拉速改变速率。采用数值模拟方法对拉速变化影响进行的研究结果同样表明,在较高拉速下发生的拉速变化,对结晶器内钢水流动有更显著的影响。

Effects of casting speed variation on non-metallic inclusion contents in the surface layer of slab in the process of continuously casting IF steel have been studied with original position statistic distribution analysis （OPA）. Its found out that when casting speed changes from higher speed （1.4 m/min） to lower one （0. 6 m/min） the effect of the casting speed on the entrapment of the mould slag primarily occurs at the initial stage of down-speed and later on the effect of down-speed and termination of down-speed at the low casting speed on the inclusion content in the surface layer of slab is insignificant. When casting speed changes from lower speed （0. 6 m/min） to higher one （1.4 m/min） the effect of speed change on the entrapment of mold flux primarily occurs at the stage of termination of up-speed as soon as it reaches the high casting rate whereas the effects of starting the up-speed and later on evenly increasing the casting speed at the lower casting speed on the inclusion content in the slab is negligible. It＇s also determined in the studies that in the stage of higher casting speed （1.4 m/min） the inclusions in the surface layer of slab increases extremely even if speed change rarely takes place. For this reason, in the higher casting speed period change of casting speed should be avoided as much as possible or lower casting rate change be adopted as best as possible. Results of experiment on the influence of the casting speed change with numerical simulation show that the effect of casting speed change at the higher drawing speed on the hot metal flowing in the mould is more prominent.