IF钢氮含量控制技术研究

Nitrogen Control Technique in IF Steel

介绍了鞍钢第二炼钢厂几年来在生产IF钢过程中对于氮成分控制方面所做的探索和研究,总结出低氮钢的生产技术和防止增氮技术。低氮钢的生产工艺包括转炉冶炼工序提高铁水比、冶炼过程控制返干、冶炼终点减少补吹次数和时间,采用铁矿石造渣,可以显著地降低转炉冶炼终点的氮含量;RH-TB精炼工序处理前期提高脱碳速度,处理中期快速提高真空度、提高提升氩气流量和钢水循环量,处理后期控制钢水中的氧含量,同时必须保证钢水极低的硫含量。防止增氮技术包括转炉冶炼工序出钢采用两步脱氧法、加强出钢口的维护、控制好大包顶渣、加强氩站吹氩操作;RH-TB精炼工序加强真空室的密封、控制合金增氮量以及大包顶渣的二次改质;板坯连铸工序控制长水口吹氩量、在长水口和大包下水口间增加新型密封垫、加强中间包密封、加强开浇操作控制、中间包大渣量操作、大包连浇操作优化、加强中间包滑板密封、开发专用保护渣等。实践表明,通过这两项技术的开发和应用,IF钢成品氮成分控制水平显著提高并趋于稳定。

The nitrogen control in IF steel production was introduced in No.2 steelmaking plant of Ansteel in recent years,and the technology of low nitrogen steel production and nitrogen pick up prevention were conclude.The low nitrogen steel production process mainly includes increasing hot metal ratio of converts charges,control on process slag returning to dry,cutting down lance reblow duration and times,forming slag by ore（sinter）,it can decrease nitrogen of converter final steel content;increasing decarburization rate of RH-TB at initial stage,increasing vacuum pressure at medium stage,increasing argon flowrate and circulation rate of steel,controlling oxygen content at later stage and super low sulphur content as well.The technique of preventing nitrogen pick up includes two steps deoxidation method at converter smelting,maintenance of tapping hole,control on top slag of ladle,operation of argon station;enhancing vacuum vessel seal in degassing process,controlling nitrogen pick up of ferroalloy and remodifing of ladle slag;controlling argon seal of ladle shroud,use new seal pad,enhancing control of start casting,adding more flux of tundish,optimization of ladle change operation,enhancing seal of the slide plate of the tundish,developing of new mould flux.According to the actual application in production of these technique,nitrogen control level of IF steel in the slabs has been improved significantly and kept more stable.