汽车板深冲用DC06 IF钢230 mm铸坯夹杂物分布研究

针对邯宝炼钢厂采用"复吹转炉-RH精炼-板坯连铸”工艺生产的IF钢铸坯，通过SLIME法电解萃 取，过滤分离,SEM及EDS等手段，对不同位置铸坯的夹杂物的数量、尺寸、成分及来源进行了系统的分析。研究表明,头坯1.5 m处的全氧、氮含量分别为70 X10^-6、47 x 10^-6 ,明显高于交接坯和正常坯;头坯2. 5m处夹杂物数量 达22. 1 mg/10 kg,是正常儕坯的27倍;铸坯头坯中夹杂物的主要成分为富含K、Na的SiO₂类夹杂，是结晶器保护 渣卷渣所致,夹杂物的尺寸主要在300 μm以内。需优化保护渣成分，粘度增大为(0.5±0.1)Pa?s,提高保护渣 A1₂O₃含量等手段降低卷渣风险。通过增加头尾坯切除量，并进行火焰清理，深冲用钢因铸坯夹杂缺陷造成的热轧 带降级率由0.3% -0.4%降至0.2%以下。

Study on Inclusion Distribution of Auto Deep-Drawing DC06 IF Steel 230 mm Casting Slab

The IF steel that produced in Hanbao steelmaking plant was followed the procedure of combined blowing converter-RH refining-slab continuous casting. The number, size, composition and source of inclusions in different positions of the slab were systematically analyzed by means of SLIME, electrolytic extraction, filtration and separation, SEM and EDS. The results showed that the total oxygen and nitrogen contents of the head slab at 1. 5 m are 70 x 10^-6 ,47 x 10 ^-6 respectively, which is significantly higher than that of the mixed and the normal slab. The number of inclusions at 2. 5 m of head slab is 22. 1 mg/10 kg, which is 27 times as high as that of the normal slab. The main composition of the inclusions in the slab is the SiO₂ inclusion rich in K and Na, which is caused by the mould slag, and the size is mainly within 300 μm. It is necessary to optimize the composition of the slag, increase the viscosity to (0. 5 ±0. 1) Pa?s, improve the slag content of Al₂0₃ and other means to reduce the risk of slag entrainment. By decreasing the amount of head and tail slab removal and flame cleaning, the degradation rate of hot strip caused by inclusions defects in deep drawing steel decreased from 0. 3% ~ 0. 4% to below 0. 2%.