炼钢 ›› 2023, Vol. 39 ›› Issue (4): 70-81.

• 凝固与浇铸 • 上一篇    下一篇

铝脱氧25Mn钢圆坯中夹杂物的分布规律

杨文魁1,宋景凌2,周  旋2,朱庆桂2,李恒华2,刘合萍2,杨   健1   

  1. 1.上海大学 材料科学与工程学院 省部共建高品质特殊钢冶金与制备国家重点实验室,上海 200444;
    2.衡阳华菱钢管有限公司 技术中心,湖南 衡阳 421001
  • 出版日期:2023-08-05 发布日期:2023-07-25

Distribution of inclusions in aluminum-killed 25Mn steel round billet

  • Online:2023-08-05 Published:2023-07-25

摘要: 针对铝脱氧25Mn钢圆铸坯中夹杂物的分布特征,通过配备夹杂物自动分析仪的扫描电镜-能谱仪(SEM-EDS)检测了圆坯不同径向位置处夹杂物的二维形貌、成分及数量密度。对钢中夹杂物进行非水电解提取及三维形貌、成分的观察,并结合FactSage 8.0软件进行了计算分析。结果表明,在钢液的凝固冷却过程中,随着温度的降低,夹杂物中Al2O3含量逐渐增加,CaS含量先增加后减少,CaO及SiO2含量逐渐减少。随着钢中氧含量的增加,单相钢液的稳定区域逐渐缩小,液相氧化物稳定区域增加。钢中夹杂物主要可分为含SiO2的S类、含Al2O3的A类、含MgO的M类及以CaO或CaS为基础的C类。随着靠近圆铸坯中心位置,夹杂物的总数量密度呈现小幅增加态势,S类、A类及M类夹杂物数量密度小幅增加,C类夹杂物数量密度小幅减少。在靠近圆铸坯表面附近,大部分CaO-Al2O3-MgO类夹杂物处于液相区附近,随着逐渐靠近圆铸坯中心处,CaO-Al2O3-MgO类夹杂物组成逐渐远离液相区域,其平均成分由液相区域逐渐转移至固相区域,夹杂物中MgO含量增加。非水电解提取到的夹杂物与夹杂物自动分析所观察到的夹杂物种类基本一致。

关键词: 夹杂物平衡相图, 夹杂物特性, 非水电解, 圆铸坯, 25Mn钢

Abstract: In view of the distribution characteristics of inclusions in aluminum-killed 25Mn steel round billets, the two-dimensional morphology, compositions and quantity density of inclusions in steel at different radial positions were analyzed with SEM-EDS equipped with an automatic inclusion analyzer. The inclusions in the steel were extracted by non-aqueous electrolysis and their three-dimensional morphologies and compositions were observed. The calculation with FactSage8.0 software was also conducted. The results show that with the decrease of temperature in the solidification and cooling process, the Al2O3 content in inclusions increases gradually, the CaS content increases first and then decreases, and the CaO and SiO2 contents decrease gradually. With the increase of [O] content in steel, the stable region of the single liquid steel phase decreases gradually, and the stable region of liquid oxide phase increases. The inclusions in steel can be mainly divided into type S containing SiO2, type A containing Al2O3, type M containing MgO and type C containing CaO or CaS. With closing to the center of the round billet, the total number density of inclusions increases slightly, the number densities of types S, A and M inclusions increase slightly, and the number density of type C inclusions decreases slightly. With closing to the surface of the round billet, the compositions of CaO-Al2O3-MgO inclusions are located near the liquid phase area. With approaching the center of the round billet, the compositions of CaO-Al2O3-MgO inclusions are gradually away from the liquid phase area. The average compositions of these inclusions are gradually transferred from the liquid phase area to the solid phase area, and the MgO content in the inclusions increases. The types of inclusions extracted with non-aqueous electrolysis are basically consistent with those observed with inclusion automatic analysis apparatus.

Key words: inclusion equilibrium phase diagram, inclusion characteristics, non aqueous electrolysis, round billet, 25Mn steel