100 t BOF-LF-RH-CC工艺冶炼结构钢时钢中氮的行为及控制

通过对淮钢100 t BOF-LF-RH-CC工艺流程冶炼45钢和42CrMo钢时各工序钢水取样分析氮含量,研究各工序对钢水中氮含量的影响。得出除吹氩和RH工序外,各工序都存在增氮现象:钢包至中间包长水口增氮占增氮总量的40%,LF精炼增氮占35%,出钢增氮占20%。所以控制转炉终点氮含量,控制LF渣层厚度,避免LF精炼补加合金和增碳,适当延长RH处理时间,提高长水口氩封效果是控制钢水氮含量的关键措施。

Behavior and Control of Nitrogen in Structural Steels Steelmaking by 100 t BOF-LF-RH-CC Process

Effect of each steelmaking stage on nitrogen content in liquid 0. 45C steel and 42CrMo steel is studied by analysis on nitrogen in sampling liquid steels at each stage of 100 t BOF-LF-RH-CC flow sheet at Huaigang Special Steel. It is obtained that there are nitrogen pick up at each stage except argon blowing and RH stage: the nitrogen pick up at long nozzle between ladle and tundish makes up 40% of the total nitrogen pick up value, that at LF refining stage makes up 35% and at BOF tapping stage makes up 20%. Therefore the key operation measures for control of nitrogen content in liquid steel are to control BOF end point nitrogen content in liquid, control LF slag layer thickness, avoid adding alloy and recarburization practice in LF refining, suitably prolong RH treatment time and increase long nozzle argon sealing effect.