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运用ANSYS和μMat Ic软件分析了980 mm纯钛锭VAR过程中熔池形貌以及凝固组织的变化规律。模拟计算结果表明:起弧阶段的熔池很小,呈浅U型;随后熔池形貌由U型逐渐变为V型;当坩埚内热量输入与输出达到平衡时,熔炼进入稳定阶段,熔池深度和宽度不再变化;补缩过程中,熔池不断缩小直至消失。凝固组织的变化规律为:与坩埚壁接触的钛液快速冷却形成细晶组织;随着熔炼的进行,以枝晶形状生长的部分细晶粒最终形成具有一定择优取向的柱状晶;铸锭中心区域和液固临界区域,晶粒直接在金属液内形核并长大,形成的等轴晶粒阻碍了柱状晶的生长,发生柱状晶-等轴转变。通过解剖工业铸锭验证,熔池形貌和凝固组织与数值模型的计算结果相吻合。
The morphology of molten pool and the variation of solidified structure in VAR process of 980 mm titanium ingot were analyzed by ANSYS and μMat Ic software. The simulation results show that the molten pool in the arc-striking phase is small and shallow U-shape, and then the shape of the molten pool is gradually changed from U-shape to V-shape. When the heat input and output in the crucible reach a balance, The depth and width of the pool no longer change; during the shrinking process, the pool continues to shrink until it disappears. The variation regularity of the solidified structure is that titanium liquid in contact with the crucible wall is rapidly cooled to form fine grain structure. As the smelting progresses, a part of fine grains growing in dendritic shape finally form a columnar crystal with a certain preferred orientation; In the region and the liquid-solid critical region, the grains nucleate and grow directly in the molten metal. The formation of equiaxed grains hinders the growth of columnar crystals and the columnar crystal-isometric transformation occurs. By anatomical industrial ingot verification, the shape of the weld pool and the solidified structure are consistent with the numerical results.