Influence of start-up arc on metallurgical quality of titanium ingot’s back-end in VAR process

Abstract:

In this paper, the numerical simulation method is used to analyze the key factors affecting the metallurgical quality of the ingot back-end from the perspective of energy input ( and heat dissipation ) at the start-up stage during VAR process. The start up stage process parameters of the third smelting process are studied and verified by experiments. The results show that the surface temperature of the ingot gradually increases with the remelting time during the start-up stage, and the surface temperature reaches the highest at the height of 30 mm ingot. By controling 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 Φ720mm TC17 titanium alloy increases by 4kA in the third remelting, and rapidly rises to a large current in 1min, then the holding time of the large current is extended by 6min, which can accelerat to bulid the molten pool, and the weight of the molten metal is reduced by about half. The numerical simulation and experimental results are in good agreement.

Key words:titanium;alloys, ingot’s;back-end, start;up stage;process, numerical;simulation