摘要
55SiCr高应力弹簧钢主要用于制造交通工具的气门、悬架和制动弹簧,钢中的大颗粒复合夹杂物所引起的疲劳破坏和长条形MnS所造成的各向异性与氢致裂纹敏感性等是降低弹簧服役寿命的重要原因。从冶炼环节对此类夹杂物进行改质改性并使其细小、无害化是提高弹簧服役性能的重要途径。基于高温管式炉冶炼试验并结合SEM、EDS检测和热力学计算等方法探究了稀土铈对55SiCr钢中夹杂物的改性机制以及铈含量对夹杂物的影响规律。结果表明,钢水中加入铈后,首先生成大量小尺寸稀土夹杂物;随着反应进行,夹杂物数量逐渐减少,大多数夹杂物得以上浮去除。适量铈可以起到净化钢液作用。此外,铈的添加量对夹杂物特性影响很大。当铈添加量为0.02%时,钢中的夹杂物主要为被铈不同程度改性的MnS夹杂以及Ce-O-S、Ce-S类夹杂,尺寸大多为1~3μm,呈球形或椭球型;当铈添加量增加至0.26%时,MnS夹杂消失,形成大量有棱角、不规则的Ce-O和Ce-O-S类夹杂,对钢的疲劳性能将产生不利影响。铈通过3种方式改性MnS夹杂,从MnS四周向内扩散进行、从MnS夹杂物一侧改性以及从MnS中部开始改性。从控制夹杂物无害化角度,建议适宜的稀土添加量为0.01%~0.02%,此时钢中铈质量分数为0.009%~0.014%。
55 SiCr high stress spring steel is the main raw material used in the manufactures of vehicle valve,suspension and braking springs.The fatigue failure caused by large-sized compounded inclusions and the anisotropy and the sensitivity of hydrogen-induced crack caused by strip MnS in the steel are the important aspects to reduce the service life and performance of the springs.The modification process of inclusions in this steel by rare earth Ce and its mechanism,along with the influence of Ce content on inclusions were studied through high-temperature tube furnace smelting experiments combined with SEM-EDS detections and thermodynamic calculations.The research results show that after adding Ce,a large number of small-sized rare earth inclusions are generated in the steel first.As the reaction progresses,the number of inclusions gradually decreases and most of them are removed.A proper amount of rare earth can purify the molten steel.Moreover,the Ce content has a great influence on the characteristics of inclusions.When it is added 0.02%,the inclusions in steel are mainly of modified MnS,Ce-O-S and Ce-S inclusions with sizes 1-3μm,spherical or ellipsoid in geometry.When the Ce addition is increased to 0.26%,the MnS inclusions disappear,generating a large number of angular and irregular Ce-O and Ce-O-S inclusions,which will adversely affect the fatigue properties of the steel.It is pointed out that MnS is modified by Ce through three ways,outside inwards,side inwards and inside outwards.To make the inclusions harmless in steel,an appropriate addition amount of rare earth is suggested to be 0.01%-0.02%,at which the mass percent of Ce in steel will reach to 0.009%-0.014%.
作者
马钰
唐海燕
刘颜彬
刘锦文
江野
张家泉
MA Yu;TANG Hai-yan;LIU Yan-bin;LIU Jin-wen;JIANG Ye;ZHANG Jia-quan(School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing,Beijing 100083,China;Special Steel Business Department,Nanjing Iron and Steel Co.,Ltd.,Nanjing 210044,Jiangsu,China)
出处
《钢铁》
CAS
CSCD
北大核心
2022年第6期57-71,共15页
Iron and Steel
基金
国家自然科学基金资助项目(51874033)
北京市自然科学基金资助项目(2182038)。
关键词
稀土
夹杂物
改性
弹簧钢
机理
MNS
rare earth
inclusions
modification
spring steel
mechanism
MnS
作者简介
马钰(1997—),男,硕士生,E-mail:ustbmy@163.com;通讯作者:唐海燕(1970—),女,博士,E-mail:tanghaiyan@metall.ustb.edu.cn,北京科技大学冶金学院钢铁冶金系教授,博士生导师,系副主任。主要从事特殊钢精炼与连铸质量控制研究,在冶金反应器设计与优化、钢水精炼、夹杂物控制、稀土在钢中的应用、电磁冶金等方面有深入研究。近五年承担国家重点研发、国家级自然科学基金、北京市自然科学基金、工业强基项目等科研项目30余项,发表学术论文40余篇。在国内率先开展感应加热中间包的设计与研发工作,并在多个钢铁企业得以应用,与企业合作率先开展轨道交通用齿轮、轴承钢以及深井油田用抗硫油套管的研发工作,均取得良好的应用效果。培养的研究生多人次获国家奖学金、学院学术之星、北京市优秀毕业生、校优秀学位论文等荣誉。主讲国家级精品课程《冶金物理化学》、国家一流课程《钢铁冶金学II》、研究生课程《冶金工艺与智能化控制》等,先后获科研工作标兵、寿昆教学名师、我爱我师-我心目中最优秀的老师、教学标兵、校十佳班主任、校先进个人等荣誉,获冶金科学技术一等奖、北京市教育教学成果一等奖等奖项。
