炼钢 ›› 2022, Vol. 38 ›› Issue (6): 58-65.

• 产品工艺与质量控制 • 上一篇    下一篇

EAF→LF→VD→CC流程SAE8620RH齿轮钢中夹杂物分析

刘  新1,战东平1,姜周华1,张慧书2,安  杰3,李  涛3,孙大利3,吴  昱3   

  1. 1.东北大学 冶金学院,辽宁 沈阳 110819; 
    2.辽宁科技学院 冶金工程学院,辽宁 本溪 117004;
    3.抚顺特殊钢股份有限公司,辽宁 抚顺 113001
  • 出版日期:2022-12-05 发布日期:2022-12-02

Analysis on inclusions of SAE8620RH gear steel produced by EAF→LF→VD→CC

  • Online:2022-12-05 Published:2022-12-02

摘要: 针对国内某钢厂采用EAF→LF→VD→CC流程生产的SAE8620RH齿轮钢中夹杂物,通过SEM-EDS和热力学计算研究了夹杂物的形成机理和演变规律。结果表明,钢中的复合夹杂物主要是以MgO·Al2O3为核心外部包裹CaS的复合形式存在。LF精炼初期夹杂物主要为MgO·Al2O3,外部包裹有少量的CaS;经过钙处理后,部分MgO·Al2O3被改性为液态钙铝酸盐;经VD真空处理后,MgO·Al2O3外部包裹的CaS比例明显增加;铸坯中MgO·Al2O3外部重新析出MnS,形成MgO·Al2O3-(Ca,Mn)S。当钢液中的w(Al)=0.03 %时,w(Mg)=1.85×10-6就可以生成MgO·Al2O3。在LF精炼初期,CaS主要是[S]和[Ca]直接反应生成,而在VD真空过程中,钢液中的[S]和[Ca]会进一步反应生成CaS,并且MgO·Al2O3外部的钙铝酸盐也会与[S]反应形成CaS。

关键词: SAE8620RH齿轮钢, 夹杂物, 形成机理, 演变机理

Abstract: The formation mechanism and evolution of inclusions in SAE8620RH gear steel produced by EAF→LF→VD→CC process in a domestic steel mill were studied by SEM-EDS and thermodynamic calculation. The results show that the oxygen-sulfur composite inclusions in steel mainly exist in the composite form of  MgO·Al2O3 as the core and CaS wrapped outside. The experimental results show that the inclusions in liquid steel at the early stage of LF refining are mainly MgO·Al2O3, with a small amount of CaS wrapped around the outside. After Ca treatment, part of MgO·Al2O3 is modified into liquid calcium aluminate. After VD vacuum treatment, the CaS proportion of MgO·Al2O3 coating increased obviously. MgO·Al2O3 in the billet precipitates MnS again, forms a composite form of MgO·Al2O3-(Ca,Mn)S. Thermodynamic calculation results show that MgO·Al2O3 can be generated when the mass fraction of Al in liquid steel is 0.03 % and the mass fraction of Mg is 1.85×10-6. In the early stage of LF refining, CaS is mainly generated by the direct reaction of [S] and [Ca], while in VD vacuum process, [S] and [Ca] in liquid steel will further reacted to form CaS, and calcium aluminate outside MgO·Al2O3 will also reacted with [S] to form CaS.

Key words: SAE8620RH gear steel, inclusions, formation mechanism, evolution mechanism