40CrB钢冶炼过程中氮含量的控制

Controlling of Nitrogen Content in 40CrB Steel Smelting Process

以莱钢50 t电炉生产线生产40CrB钢的冶炼过程为对象,分析含硼钢冶炼过程中氮含量的变化情况。结果表明:氮含量呈先降低后增加再降低再增加的变化趋势,整个冶炼过程电炉终点氮含量最低,连铸坯氮含量最高,VD处理有利于降低氮含量;电炉出钢至精炼阶段,氮含量增加最为明显,其次是连铸阶段。通过控制铁水(或生铁)兑入比例、精炼渣量、VD炉操作和保护浇铸,钢中氮含量可以控制在50×10-6以下。

Taking the smelting process of producing 40CrB steel in Laiwu Steel’s 50 t electric furnace line as research object, the nitrogen content change of boron steel in smelting process was analyzed. The results showed that the nitrogen content is first decreased and then increased and then decreased trend to increase. In smelting process, the nitrogen content is lowest in the end of EAF and is highest in the billet. VD treatment is propitious to decrease the nitrogen content. From EAF tapping to the refining stage, the nitrogen content increases most obviously and secondly in continuous casting stage. By controlling the mix population of liquid iron （or pig iron）, the amount of refining slag, the operation of VD furnace and protective casting, the nitrogen content would be controlled below 50×10-6.