齿轮钢锻件关键区域氧化物和硫化物夹杂的分布特征

齿轮是机械传动的关键结构部件,为了改善齿轮的服役性能,提高疲劳寿命,需要清楚齿轮钢中的夹杂物类型、数量、尺寸、分布。采用夹杂物自动扫描仪、氧含量分析手段、扫描电镜对齿轮钢锻件不同位置进行夹杂物评估。结果表明:铸件中心位置TO质量分数较高,为10×10-6,对应小尺寸夹杂物数量较多,而大尺寸夹杂物在关键区域的分布较多。钢中氧化物夹杂主要为Al2O3、Al2O3复合类的尖晶石和钙铝酸盐复合夹杂物,且尺寸较大,分布不均匀,对齿轮钢关键区域的影响较大。钢中硫化物夹杂分布均匀,尺寸较小,热力学计算表明,该类夹杂在凝固过程中凝固率g>0.44时,MnS开始析出,通过控制硫化物夹杂析出及分布有助于改善齿轮钢质量。

Distribution characteristics of oxides and sulfide inclusions in key areas of gear steel forgings

Gears are key structural components of mechanical transmission. In order to improve the service performance of gears and improve the fatigue life, it is necessary to know the type, quantity, size and distribution of inclusions in gear steel. Inclusions were evaluated at different positions of gear steel forgings using an automatic inclusion scanner, oxygen content analysis method, and scanning electron microscope. The total oxygen content in the center of the casting is higher, which is 10×10-6, corresponding to the large number of small sized inclusions, and the large sized inclusions are distributed in key areas. The oxide inclusions in the steel are mainly Al2O3, Al2O3 composite spinel and calcium aluminate composite inclusions, and the size is large and the distribution is uneven, which has a greater impact on the key areas of gear steel. The distribution of sulfide inclusions in the steel is uniform and the size is small. Thermodynamic calculations show that MnS begins to precipitate when the solidification rate g>0.44 during the solidification process. By controlling the precipitation and distribution of sulfide inclusions, it helps to improve the quality of gear steel.