GCr15轴承钢BOF-LF-RH-CC流程夹杂物的生成及演变  被引量:8

Formation and evolution of inclusions in GCr15 bearing steel produced by process of BOF-LF-RH-CC

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作  者:王康豪 姜敏[1] 李凯轮 王新华[1] WANG Kang-hao;JIANG Min;LI Kai-lun;WANG Xin-hua(School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing,Beijing 100083,China)

机构地区:[1]北京科技大学冶金与生态工程学院,北京100083

出  处:《钢铁》2022年第10期64-72,共9页Iron and Steel

基  金:国家重点研发计划资助项目(2021YFB3401001);中央高校基础科研业务费资助项目(FRF-DF-20-08)。

摘  要:为研究GCr15轴承钢中夹杂物的演变规律,对某钢厂BOF-LF-RH-CC工艺流程生产的GCr15轴承钢进行了全流程取样,并利用ASPEX扫描电镜和热力学计算对各工序钢中夹杂物的演变进行了系统的分析。研究表明,在LF精炼初期,钢中夹杂物主要为高Al_(2)O_(3)(w(Al_(2)O_(3))=84%)的MgO-Al_(2)O_(3)和CaO-MgO-Al_(2)O_(3)夹杂物;LF精炼结束时,MgO-Al_(2)O_(3)和CaO-MgO-Al_(2)O_(3)夹杂物的数量所占比例分别为74%和26%,此时钢液中夹杂物尺寸主要为1~6μm,数量所占比例为87%。LF-RH精炼期间,夹杂物总数量由LF精炼结束时的198个/(20 mm^(2))降低至RH破空后的103个/(20 mm^(2)),降幅为48%,其中MgO-Al_(2)O_(3)夹杂物主要在LF精炼期间生成,然后在RH精炼时基本被去除,具体表现为,其数量由LF进站时的88个/(20 mm^(2))增加至LF出站时的139个/(20 mm^(2)),在RH软吹结束时降低为4个/(20 mm^(2));CaO-MgO-Al_(2)O_(3)夹杂物主要在RH精炼期间生成,其数量由LF出站时的49个/(20 mm^(2))增加至RH软吹结束时的108个/(20 mm^(2)),这表明RH真空精炼对夹杂物去除效果较好。热力学计算结果表明,二次精炼过程中钢中Al_(s)、Mg含量处于MgO-Al_(2)O_(3)夹杂物优势区内,这表明MgO-Al_(2)O_(3)夹杂物更易生成;当钢中w([Mg])为0.0003%时,w([Ca])大于0.00025%,满足MgO-Al_(2)O_(3)夹杂物转变为CaO-MgO-Al_(2)O_(3)夹杂物的热力学条件,而且当w([Al_(s)])为0.022%时,w([Ca])控制为0.00025%~0.00700%时更有利于生成液态化的钙铝酸盐。试验过程钢中w([Ca])约为0.0001%~0.0004%,因此夹杂物更多地转变为CaO-MgO-Al_(2)O_(3)夹杂物。To study the evolution of inclusions in GCr15 bearing steel,the GCr15 bearing steel produced by BOF-LF-RH-CC process was sampled in various stages in a steel factory.The evolution behavior of inclusions in various processes was systematically analyzed by ASPEX scanning electron microscopy and thermodynamic calculation.The result indicates that due to the strong deoxidation of aluminum after the converter,at the beginning of LF refining,the inclusions in molten steel consists of MgO-Al_(2)O_(3) binary system and CaO-MgO-Al_(2)O_(3) ternary system with high Al_(2)O_(3)(w(Al_(2)O_(3))=84%);the account of MgO-Al_(2)O_(3) binary system and CaO-MgO-Al_(2)O_(3) ternary system are 74% and 26% at the end of LF refining.At this moment,the inclusions in the liquid steel have a size distribution from 1 to 6 μm account for 87%.During refining from LF to RH,the total number of inclusions decreased from 198 pcs/(20 mm^(2)) at the end of ladle furnace refining to 103 pcs/(20 mm^(2)) at the end of RH vacuum degassing,a drop of 48%.Among them,MgO-Al_(2)O_(3) binary system were mainly generated during LF refining,and then removed during RH refining,specifically,the number increased from 88 pcs/(20 mm^(2)) at the beginning of LF refining to 139 pcs/(20 mm^(2)) at the end of LF refining,and after the end of RH soft blowing,it was reduced to 4 pcs/(20 mm^(2));CaO-MgO-Al_(2)O_(3) ternary system were mainly generated during RH refining,and their number increased from 49 pcs/(20 mm^(2)) at the end of ladle furnace refining to 108 pcs/(20 mm^(2)) at the end of RH soft blowing.This shows that RH vacuum refining has a better effect on inclusion removal.Thermodynamic calculations show that the contents of Al_(s) and Mg in the liquid steel are in the MgO-Al_(2)O_(3) inclusion formation region during the secondary refining process,indicating that MgO-Al_(2)O_(3) inclusions are easier to form;When w([Mg])in the liquid steel is 0.000 3% and w([Ca]) is greater than 0.000 25%,the thermodynamic conditions for the transformation of MgO-Al_(2)O_(3)

关 键 词:GCR15 夹杂物 轴承钢 精炼 演变 

分 类 号:TF762.4[冶金工程—钢铁冶金]

 

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