钛合金铸锭尾部冶金质量影响因素研究

Influence Factors of Metallurgical Quality of Titanium Ingot’s Back-End in VAR Process

采用数值模拟方法,通过从熔炼起弧阶段的能量输入(以及散热)的角度分析影响铸锭尾部冶金质量的关键因素,对第3次熔炼的起弧工艺参数进行研究,并通过实验进行了验证。结果表明,电流起弧后随着熔炼的进行,铸锭表面温度逐渐升高,在熔炼至铸锭30mm高度处,表面温度达到最高。通过选择合适时机提升起弧电流大小,加快电流上升速度,可以使熔池表面温度明显上升。Φ720 mm规格TC17钛合金第3次熔炼起弧电流增大4 kA,1 min快速升至大电流,大电流保持时间延长6 min,能够实现熔池快速健全,达到稳定熔池时熔炼的金属质量减少约一半,数值模拟和实验结果的一致性吻合良好。

The key factors affecting the metallurgical quality of the ingot’s back-end from the perspective of energy input(and heat dissipation)at the start-up stage during vacuum arc remelting(VAR)process were analyzed by the numerical simulation method.The start-up stage process parameters of the third smelting process were studied and verified by experiments.The results show that the surface temperature of the ingot gradually increases with the prolongation of remelting time during the start-up stage,and the surface temperature reaches the highest at the ingot height of 30 mm.By controlling the appropriate time to increase the arc current and accelerate the current rise rate,the surface temperature of the molten pool can be significantly increased.The arc current of TC17 titanium alloy ofΦ720 mm increases by 4 kA in the third remelting and rapidly rises to a large current in 1 min,then the holding time of the large current is prolonged by 6 min,which can accelerate the molten pool formation,and the mass of the molten metal is reduced by about half.The numerical simulation and experimental results are in good agreement.