120t BOF-LF-180mm×180mm坯连铸-连轧流程生产易切削钢1215工艺实践

Process Practice of 1215 Free Cutting Steel Produced by 120t BOF-LF-180mm×180mm Billet Casting-Continuous Rolling Flowsheet

成功开发了1215易切削钢120 t转炉-120 t LF-180mm×180mm连铸-高线轧制生产工艺。关键控制点为:转炉出钢C<0.05%、转炉终点温度1630~1660℃、精炼自由氧控制目标50×10^-6~55×10^-6,炉渣二元碱度2.5~3.0。设计成分(/%)为:0.05~0.07C,1.20~1.35Mn、0.340~0.360S,该工艺条件下钢中硫化物形貌和含量控制合理,Mn/S有利于易切削钢的轧制和改善切削性能。钢水的过热度按25~40℃控制,拉速1.2 m/min。实践表明,准确预判终点氧含量以确定脱氧剂加入量,合理控制不同工序的氧含量是达到线材产品质量稳定的关键。

The 1215 free cutting steel is successfully developed by 120 t converter-120 t LF-180mm×180mm billet casting high-speed wire rolling flowsheet.The key control point is converter tapping steel C<0.05%,converter end temperature 1630~1660℃,refining free oxygen control target 50×10^-6~55×10^-6,and binary slag basicity 2.5~3.0.The composition design is 0.05%~0.07%C,1.20%~1.35%Mn,and 0.340%~0.360%S.On this process conditions,the morphology and content of sulfide in steel are controlled reasonably.The Mn/S is beneficial to the rolling and improving cutting performance of free cutting steel.The superheat of molten steel is controlled within 25~40℃and the casting speed is 1.2 m/min.It shows that accurately predicting the end-point oxygen content to determine the amount of deoxidizer added,and reasonable control of the oxygen content of different processes are the key to achieve stable quality control of wire products.