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为了改善20CrMnTi小方坯的凝固组织,采用移动边界法先对20CrMnTi钢的温度场进行模拟,在此基础上,采用元胞自动机有限元法(CAFE法)对其凝固组织进行了数值模拟。当模拟结果与实际结果基本吻合时,进一步探讨了硅、铬、锰、钛等合金元素对20CrMnTi钢凝固组织的影响规律。模拟结果表明,在该钢号的合金元素规定范围内,适当减少硅元素的质量分数,能够提高铸坯中心等轴晶比例,使晶粒数目增加,晶粒平均半径减小。适当添加铬元素能够扩大铸坯中心等轴晶区,从而减小晶粒平均半径,增加晶粒数量。增加锰元素质量分数可以提高铸坯的中心等轴晶率。最后根据所得模拟结果对该钢种的合金元素进行调整,达到了扩大铸坯中心等轴晶区和细化晶粒的目的。
In order to improve the solidification microstructure of 20CrMnTi billet, the moving boundary method was used to simulate the temperature field of 20CrMnTi steel. Based on this, the solidification microstructure of the 20CrMnTi steel was numerically simulated by CAFE method. When the simulation results are in good agreement with the actual results, the influence of alloying elements such as silicon, chromium, manganese and titanium on the solidification microstructure of 20CrMnTi steel is further discussed. The simulation results show that the appropriate reduction of the mass fraction of silicon within the specified range of alloying elements of the steel can increase the proportion of equiaxed grains in the center of the slab, increase the number of grains and decrease the average radius of grains. Appropriate addition of chromium can enlarge the center equiaxed zone of the slab, so as to reduce the average grain radius and increase the number of grains. Increasing the mass fraction of manganese can increase the center equiaxed rate of slab. Finally, according to the simulation results obtained, the alloying elements of the steel are adjusted to achieve the purpose of expanding equiaxed grains in the center of the slab and grain refinement.