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针对某厂20CrMnTi齿轮钢生产过程中全氧含量控制偏高,夹杂物控制水平差等问题,研究利用FactSage热力学软件计算结果着重探讨精炼渣碱度、w(CaO)/w(Al_2O_3)、MI指数与Al_2O_3夹杂吸附能力的影响关系,最终得到适用于该厂生产齿轮钢(20CrMnTi)的LF精炼渣系范围为:w(CaO)=50%~55%,w(Al_2O_3)=22%~26%,w(SiO_2)=10%~12%,w(MgO)=5%~7%。使用该渣系进行工业试验,铸坯中全氧质量分数由17×10~(-6)降至14×10~(-6),且铸坯中显微夹杂物尺寸也明显降低,由2.0μm降至1.4μm,且工艺优化后铸坯中观察到的绝大部分夹杂物都在1 500℃液相线以内变化,夹杂物变性效果良好。
Aiming at the problems of high total oxygen content control and poor control of inclusions in the production process of a 20CrMnTi gear steel in a certain plant, the calculation results of FactSage thermodynamic software are used to investigate the effects of refining slag alkalinity, w (CaO) / w (Al 2 O 3) The results show that the LF refining slag system suitable for 20CrMnTi gearbox is as follows: w (CaO) = 50% ~ 55%, w (Al_2O_3) = 22% ~ 26% , w (SiO 2) = 10% to 12%, and w (MgO) = 5% to 7%. Using this slag system for industrial experiments, the mass fraction of oxygen in the slab decreased from 17 × 10 -6 to 14 × 10 -6, and the size of micro-inclusions in the slab decreased obviously from 2.0 μm to 1.4 μm, and most of the inclusions observed in the slab after process optimization all changed within the liquidus of 1 500 ℃, and the denaturing effect of inclusions was good.