VD过程钢液氮含量控制工艺研究与实践

Research and practice on control of nitrogen contents during VD process

对某厂230 t VD处理过程的氮含量控制进行了研究。分别从真空度、底吹强度、真空处理时间等工艺参数及硫、氧等钢液成分对VD脱氮的影响进行了分析。分析表明:降低钢液初始氮含量,严格控制钢中的硫、氧含量,增强底吹强度,延长高真空保持时间对生产低氮钢有利;对VD破真空后钢液增氮的原因进行了分析,并提出:适当改变破真空操作制度、调整软吹流量,可以减少钢液增氮。

The process of nitrogen content controlling in VD is studied in this paper and the impact of parameters such as vacuum, bottom blown flux, vacuum processing time etc. and chemical compositions such as sulfur, oxygen and nitrogen in liquid steel on denitrification is analyzed separately. The analysis indicates that such a few processing measures as reduction of the initial nitrogen content, strictly control of the sulfur and oxygen contents during VD process, enhancement in the strength of bottom blowing, extension of the holding time of vacuum pressure are favorable for production of the low nitrogen steel. The reason for increase of nitrogen contents after vacuum break is ana- lyzed and in the end its pointed out that the nitrogen pick up in the liquid steel can be re- duced by appropriately changing the vacuum break operating schedule, and readjusting the soft blowing rate.