【作者】 王新华； 姜敏； 于会香； 汪开忠； 孙维；

【Author】 Wang Xinhua;Jiang Min;Yu Huixiang;Wang Kaizhong;Sun Wei;School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing;Technical Research Center, Ma Steel Co., Ltd.;

【机构】 北京科技大学冶金与生态工程学院； 马鞍山钢铁有限责任公司技术中心；

【摘要】 作者对采用"EAF-LF-RH-CC"冶金工艺生产的高铁车轮、车轴钢中大型非金属夹杂物和宏观偏析的控制技术开展了试验研究,发现:超低氧含量（T.O<6ppm）铸坯中尺寸大于100mm的夹杂物全部为在连铸过程聚合形成的簇群状夹杂物,而铸坯宏观偏析主要表现为由铸坯边部至中心正负偏析交替发生的"W"形偏析。高铁轮轴钢LF精炼中,钢液中夹杂物发生由Al₂O₃向Mg O-Al₂O₃系、Ca O-MgO-Al₂O₃系、CaO-Al₂O₃系夹杂物的顺序转变。由于固态夹杂物与钢液间表面张力大而更易去除,因此开发了更高效的二次精炼工艺,其特点主要为:（1）尽可能地缩短LF精炼时间,以延缓固态夹杂物向液态夹杂物的转变;（2）将RH精炼时间延长至33min以上以更充分发挥其去除夹杂物能力,使RH精炼后钢液中夹杂物近乎全部为在其后连铸过程不易聚合的微小液态夹杂物。研究证实"W"形宏观偏析主要与结晶器电磁搅拌（M-EMS）和铸流区电磁搅拌（S-EMS）作用有关,通过采取措施大幅后移S-EMS位置并采用"弱M-EMS/弱S-EMS/中F-EMS"电磁搅拌功率控制模式,解决了长期困扰特殊钢连铸的"W"形宏观偏析问题。直径450mm和600mm连铸圆坯碳含量波动值低于0.03%,最大偏析度（C/C₀）降低至1.03以下。更多还原

【Abstract】 Investigation was made on control of large-sized inclusions and macro segregation in high speed train wheel and axle steels produced by EAF-LF-RH-CC steelmaking route. It was found that, in the continuously cast round blooms containing less than 6 ppm T.O, the inclusions larger than 100mm were all the cluster typed inclusions formed due to aggregation of small inclusion particles in liquid steel in continuous casting and the macro segregation behaves like the letter "W", i.e. negative and positive segregations took place alternatively from edge to center of the bloom. In LF refining of the steels, the inclusions were found to transfer from Al₂O₃ firstly to Mg O-Al₂O₃, then to CaO-MgO-Al₂O₃ and finally to CaO-Al₂O₃ system. As the solid inclusions of Al₂O₃, MgO-Al₂O₃ and CaO-MgO-Al₂O₃ have larger contact angles and are easy to be removed, measures were taken:（1） Delay the transfer of the solid inclusions to liquid ones of Ca O-Al₂O₃ system by shorten as much as possible the LF refining time and,（2） eliminate most solid inclusions in RH degassing by extending the RH refining time to more than 33 min. With this technique, the remnant inclusions after RH were mostly small-sized liquid inclusions which were difficult to aggregate to larger inclusions in subsequent continuous casting.The "W" typed macro segregation was proved mainly due to actions of M-EMS and S-EMS in continuous casting. By largely moving the position of S-EMS far from the meniscus and adopting the EMS power control pattern of "Week M-EMS/Week S-EMS/Middle F-EMS", the long term problem of "W" typed macro segregation in continuous casting of special steels were solved. The carbon variation range of wheel and axle steel blooms of ?450 mm and ?600 mm has been decreased to less than 0.03% and the maximum segregation degree of carbon（C/C₀） lowered to less than 1.03.更多还原