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How did you get the titanium in your hand (4)? Production of titanium ingots

In the previous articles, we learned how titanium is refined from ore, to titanium tetrachloride, and then to sponge titanium.
Today, we continue to delve into the production process of titanium alloys, which is the production of titanium alloy ingots!
From this point on, we entered the production and business scope of the titanium metal material company.
How did you walk step by step?
Firstly, sponge titanium is a high-purity titanium metal. In order to improve the physical properties of the material, we need to add some other metals. The common titanium alloy code is TC4, full name Ti-6Al-4V, which belongs to the (α+β) type titanium alloy. It is an alloy package that adds aluminum vanadium metal to titanium metal.
This production process is the production of titanium alloy ingots.
This process, called "melting", can be imagined as squeezing sponge titanium and aluminum vanadium into candles, then burning the candles upside down. After multiple melting processes, a homogeneous metal ingot is formed. This process is the production of titanium alloy ingots.
Vacuum arc remelting is a vacuum melting technology that uses an arc as a heat source to melt metals under vacuum conditions, abbreviated as VAR.
First, let's build a simple model: light a candle, and the normal situation is that the flame is facing upwards. The melting of titanium material is exactly the opposite, it's like flipping a candle upside down with the flame facing downwards. Dropping wax into the crucible becomes a titanium ingot.
The true principle of melting titanium materials is that, under slag free and vacuum conditions, the metal electrode rapidly melts under the high temperature of a direct current arc and undergoes re solidification in a water-cooled copper crystallizer.
The process of vacuum arc remelting can be divided into four stages: welding electrode, arc initiation, normal melting, and capping
(1) Welding electrodes. The consumable electrode used in each furnace of smelting must be coaxial with the transition electrode and firmly welded to the transition electrode. Welding is carried out under vacuum. Lay a layer of vehicle debris of the same type as the arc starter on the end where the consumable electrode is welded, then lower the electrode rod to ignite an arc between the transition electrode and the consumable electrode. When the two end faces of the arc are heated and the arc is stable, and a large amount of metal liquid phase is formed on the consumable electrode end face, quickly lower the electrode rod to make the two end faces of the arc tightly contact and weld together.
(2) Start the arc.
Ignite an arc between the consumable electrode and the fine pure titanium sponge at the bottom of the crystallizer, increase the temperature of the arc zone, and form a certain size of metal melt pool at the bottom of the crystallizer, maintaining a stable arc between the consumable electrode and the metal melt pool, and enabling the remelting of the consumable electrode to transition to normal melting.
(3) Melting period.
It is the main period of the remelting process, during which titanium or titanium alloys are melted and solidified into ingots, removing gases and low melting point metal impurities from the metal, removing non-metallic inclusions, reducing segregation degree, and obtaining ideal as cast microstructure.
(4) Capping (also known as shrinking).
The purpose is to reduce the shrinkage cavity at the head of the remelted ingot, alleviate the looseness of the "V" - shaped shrinkage zone at the head, promote the upward floating and elimination of inclusions, reduce the cutting amount, and improve the yield.
At this point, we have finally obtained the titanium alloy ingot. Don't worry, there are still many processes ahead to make it into a finished product. Let's talk about it step by step!

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