工艺条件对大规格TC4扁锭连铸过程固液界面的影响

Effect of process condition on solid liquid interface during continuous solidification process of large scale TC4 titanium alloy slab ingot

利用有限元方法对电子束冷床熔炼大规格TC4扁锭连续凝固过程温度场进行计算分析,研究不同铸造工艺条件下熔池形貌特征以及固液界面曲率的变化,并且定量地给出固相线和液相线位置以及糊状区深度的变化规律。结果表明:随着浇注温度的升高,TC4扁锭的液相线和固相线深度加深、宽度变宽,而固相线与液相线之间的糊状区变窄;随着拉锭速度的加快,熔池加深变宽,糊状区逐渐变宽,温度梯度变小,固相率逐渐减少;但拉锭速度对固液界面形貌的影响相对于浇注温度的影响更为显著,在本计算模拟条件下,拉锭速度应控制在3.5×10^(-4)m/s以下。

The continuous solidification process of the large scale TC4 titanium alloy during electron beam cold hearth melting was computational analyzed by using finite element method in order to study the temperature field distribution,which focused on the feature of the molten pool and the change of curvature of solid-liquid interface at the different process conditions.In addition,it is quantitatively given that the relationship of the situation of solidus and liquidus and the depth of mushy zone with different process conditions.The results show that under the same pulling speed,the deepening and widening of the liquidus and solidus of the TC4 titanium alloy slab ingot are caused by increasing of pouring temperature.While with the increase of pouring temperature,the mushy zone between liquidus and solidus shallows.Under the same pouring temperature,the deepening and widening of the molten pool and the mushy zone,reducing of the temperature gradient and decreasing of the solid fraction are caused by increasing of pulling speed.However,the effect of pulling speed on the solid-liquid interface morphology is more remarkable than pouring temperature,the pulling speed should be controlled under 3.5×10-4 m/s in this computational condition.