开浇第一炉连铸坯夹杂物形成原因与控制措施

Reasons and Control Measures of Inclusion in First Slab

应用氮成分分析、Al烧损分析、硫印分析等分析方法,研究了转炉—LF—RH—连铸机生产宽厚板连铸坯开浇第一炉夹杂物形成原因及控制措施。结果表明。通过优化软吹工艺、增设中间包吹氩、减少开浇出苗时间、提高开浇操作水平、快速提拉速与减少浸人式水口插入深度,开浇第一炉连铸坯夹杂物含量比原来明显减少;同时,第一炉表面夹杂缺陷率大大降低,由优化前的42.1%降低为10.5%;铸坯中夹杂物在厚度方向上分布不均匀,铸坯厚度1/4处夹杂物较多。铸坯厚度中心有夹杂物聚集现象;在铸坯宽度方向的边部,钢中所含夹杂物较少;在铸坯宽度方向1/4处,钢中夹杂物显著增多;在铸坯中部.夹杂物明显增加。

The reasons and control measures of inclusion in first wide heavy slab produced by BOF-LF-RH-CCM were studied by means of[N]content analysis,aluminum burning loss analysis,Sulfur Print,etc.It is found that the inclusion contents of first slab obviously decreasing and the defect rate of surface inclusion was reduced from42.／%to 10.5%through optimization of soft blowing process,Argon blowing in tundish,minimizing mould filling time,promoting operating level of start casting and accelerating casting speed fast.The distribution of inclusions was non-homogeneous along both thickness and wideness direction of slab.The inclusions assembled in 1/2 position and in 1/4 at board base thickness and width direction.