小方坯连铸20CrMnTiH齿轮钢宏观偏析控制

Study on Macro Segregation Control of Continuous Casting Billet in Gear Steel 20CrMnTiH

针对小方坯连铸齿轮钢偏析严重的问题,采用化学元素分析以及原位分析仪分析了断面碳元素的分布情况,通过低过热度、拉速、电磁搅拌以及二冷水试验,确定了最佳连铸工艺参数。工业应用试验表明,过热度采用20℃±5℃,拉速采用1.30 m/min,结晶器电磁搅拌和凝固末端电磁搅拌的电流强度分别采用250 A和50 A,二冷水比水量采用0.41L/kg有利于偏析控制,铸坯断面碳偏析指数控制在0.94~1.05,棒材断面硬度(HV)控制在±10以内。

In order to control the macro-segregation of gear steel,the chemical analysis and original position analyzer were applied on carbon distribution of billets in cross section.The superheat,casting speed,electromagnetic stirring and flowrate of secondary cooling testes had been performed and the optimal casting parameters were determined.The test results show that superheat range should be controlled at 20℃±5℃and casting speed should beat 1.30 m/min.The current intensity of M-EMS and F-EMS should be 250 A and 50 A respectively.The flowrate of secondary cooling should be 0.41 L/kg.These parameters were benefit to the macro segregation control.The industrial results indicated that carbon segregation indexes of billets in cross section were 0.94 to 1.05 and hardness variation of bar at cross section were at±10 HV range.