基于镁处理的含硫齿轮钢硫化物形态控制

Sulfide morphology control of sulfur-bearing gear steel based on magnesium treatment

为考察镁变质夹杂物对含硫齿轮钢中硫化物形态的控制效果,对加硫40Cr钢进行镁处理,结合热力学分析,解析了冶炼和轧制过程夹杂物的演变行为。研究结果表明,金属镁添加到钢液中后,可将钢中Al_(2)O_(3)夹杂变质为弥散分布的MgAl_(2)O_(4)夹杂;在凝固过程中,变质后的MgAl_(2)O_(4)夹杂可以作为硫化锰的析出核心形成复相夹杂;在轧制过程中,核心的MgAl_(2)O_(4)可进一步发挥骨架作用而抑制周边硫化锰的延展,有效降低了硫化锰的长径比,预期有利于齿轮钢切削性能和机械性能的改善。研究结果还表明,欲充分发挥MgAl_(2)O_(4)的骨架作用,需要保证钢中具有足够高的溶解镁含量使Al_(2)O_(3)充分变质,并促使MgAl_(2)O_(4)具有合适的粒度和数量,以成为控制硫化锰析出与变形的有效核心。

To investigate the controlling effect of magnesia inclusions on the sulfide morphology in sulfur-containing gear steel,this study performed magnesium treatment on 40Cr steel bearing sulfur.Combining thermodynamic analysis,the evolution behavior of inclusions during smelting and rolling processes was analyzed.The research findings revealed that after introducing metallic magnesium into the molten steel,the Al_(2)O_(3)inclusions in the steel could be transformed into dispersed MgAl_(2)O_(4)inclusions.During the solidification process,the transformed MgAl_(2)O_(4)inclusions could serve as the precipitate core of sulfide manganese,forming multiphase inclusions.During the rolling process,the core MgAl_(2)O_(4)further played a skeletal role,inhibiting the extension of surrounding sulfide manganese.This effectively reduced the aspect ratio of sulfide manganese and is expected to improve the cutting and mechanical performance of gear steel.The research results also indicated that to fully utilize the skeletal role of MgAl_(2)O_(4),it was necessary to ensure a sufficiently high dissolved magnesium content in the steel for the full transformation of Al_(2)O_(3),and to promote suitable particle size and quantity of MgAl_(2)O_(4)to serve as an effective core for controlling sulfide manganese precipitation and deformation.