Vacuum consumable arc melting is the most mature and widely used process for producing titanium and titanium alloy ingots. The principle is to use a pre pressed and welded electrode (composed of sponge titanium and intermediate alloy) as the cathode, a water-cooled copper crucible as the anode, and continuously melt the end of the electrode through a strong direct current arc (current up to tens of thousands of amperes) in a high vacuum or inert atmosphere of 10 ⁻ Pa level.
Molten metal falls into the crucible in the form of droplets to form a molten pool, and solidifies into ingots layer by layer from bottom to top under strong water cooling. To ensure high uniformity of composition and structure, 2-3 remelting processes must be carried out: the first melting is aimed at alloying and basic forming; Subsequent remelting is used for further purification, elimination of segregation, and refinement of grains. The technical essence of VAR process lies in the precise control of melting thermodynamics. By adjusting the current, voltage, melting rate, and the strength and distribution of the stable arc magnetic field, the shape, depth, and temperature gradient of the molten pool can be precisely controlled, thereby controlling the solidification direction and obtaining ideal columnar or equiaxed crystal structures. This process is stable and reliable, and is the mainstream method for producing large-sized and high-quality ingots for key forgings such as aircraft engine rotors and aircraft main load-bearing structural components.
