Vacuum Arc Remelting (VAR) is currently the mainstream process for manufacturing  titanium and titanium alloy  ingots. It eliminates titanium melt contamination through a high-vacuum environment and water-cooled copper crucible design, enabling the production of high-end ingots with exceptional purity and uniformity.

1. Fundamental Principle

VAR remelting is conducted in a high-vacuum environment, where a high-temperature arc exceeding 3000 °C forms between the metal consumable electrode (cathode) and the water-cooled copper crucible (anode), continuously melting the electrode. Molten droplets fall into the bottom of the crucible to form a molten pool, which undergoes directional solidification from bottom to top into an ingot via forced water circulation cooling. The electrode is automatically lowered as it melts to maintain a constant arc length, ensuring continuous ingot growth.

1. High Purity: The high-vacuum environment removes volatile impurities and interstitial gases such as hydrogen (H), nitrogen (N) and oxygen (O), significantly reducing their content in the ingot.

2. Contamination-Free Melting: The entire process uses a water-cooled copper crucible with no contact with refractory materials, completely eliminating refractory inclusion contamination in the titanium melt.

3. Uniform Composition: Arc electromagnetic stirring and molten pool convection promote uniform distribution of alloying elements and reduce both macrosegregation and microsegregation.

4. Dense Structure: Directional solidification and feeding eliminate defects such as central shrinkage cavities and porosity, resulting in an ingot with near-theoretical density.

5. High Flexibility: It can produce ingots of various specifications ranging from a few kilograms to 32 tons in a single heat, covering commercially pure titanium and the vast majority of titanium alloy grades.

6. Mature Process: After decades of development, a complete process and quality control system have been established, ensuring excellent batch-to-batch product consistency.

Currently, more than 90% of wrought titanium and titanium alloy ingots worldwide are produced via the VAR process, and almost all critical aerospace titanium alloy components are manufactured from ingots produced by triple VAR remelting.

1.Raw Material Preparation and Electrode Fabrication

Weigh titanium sponge and master alloys accurately per target composition.

Use two-stage mixing/charging to prevent particle segregation.

Press into electrode briquettes; vacuum plasma weld into monolithic consumable electrode.

2.Furnace Loading and Pre-Melting Preparation

Inspect water-cooled copper crucible; install electrode and adjust coaxiality.

Place titanium sponge on ingot starter as arc initiator.

Evacuate to ≤1 Pa (conventional) or ≤0.1 Pa (aerospace-grade) vacuum.

Perform helium leak detection; ensure furnace leakage rate ≤0.8 Pa/min.

3. Melting Process

Arc Ignition: Apply 60–70 V no-load voltage; strike arc at 1/4–1/3 nominal current to establish stable molten pool.

Stable Melting: Ramp current to kA–tens of kA; match voltage 28–38 V, arc-stabilizing current 8–15 A; maintain constant melting rate and real-time arc length adjustment.

Feeding: Start at 10–15% electrode remaining; gradually reduce current/rate; perform hot topping to eliminate central shrinkage and porosity.

4.Cooling and Discharging

Cut power after feeding. Keep ingot under vacuum water cooling for ≥30 min. Vent and discharge only when surface temperature <200 °C.

5. Post-Treatment of Ingots

Remove defective bottom (20–50 mm) and top (150–180 mm) sections.

Lathe-turn ingot body 10–30 mm deep to eliminate surface defects.

Conduct full composition analysis, microstructure exam and NDT. Transfer to next process only after passing all inspections.

• Electrode Fabrication: Control interstitial impurities in titanium sponge/master alloys; use two-stage mixing for uniform composition; ensure electrode briquette density/strength; maintain electrode-to-crucible diameter ratio 0.78–0.92; use vacuum plasma welding for inclusion-free welds.

• Vacuum & Airtightness: Pre-melting vacuum ≤1 Pa (conventional), ≤0.1 Pa (aerospace), 1×10⁻²–1×10⁻³ Pa (ultra-high-purity); maintain stable vacuum during melting; furnace leakage rate ≤0.8 Pa/min.
• Current & Voltage: Current based on ingot specs/alloy type; voltage 28–38 V; match parameters to stabilize arc and pool shape.
• Melting Rate: Electronically controlled constant rate 10–35 kg/min; rate-to-electrode diameter ratio 0.015–0.035 kg/(min·mm); fast rate increases axial segregation; slow rate causes segregation inheritance/low efficiency.
• Electrode Gap: Arc length 20–50 mm ; auto-controlled via voltage feedback; large gap causes arc blow; small gap causes short-circuiting.
• Arc Stabilization & Stirring: Transverse alternating magnetic field for bidirectional pool stirring; arc-stabilizing current 8–15 A; commutation cycle-to-crucible diameter ratio 0.08–0.14 s/mm; suppresses arc blow, enhances convection, reduces macrosegregation.
• Feeding Process: Start at 10–15% electrode remaining; gradually reduce current to avoid rapid solidification; duration ≥30 min; dynamically optimize based on pool conditions.
• Multiple Remelting: Minimum 2 passes; 3 passes for high-end aerospace; at least one pass uses inverted ingot as electrode to reduce axial segregation; 1st pass removes volatiles; 2nd/3rd passes improve composition uniformity.

Ruihang Group mainly produces titanium products with the complete industry chain,including smelting,forging, straightening,rolling,surface treating,testing process. For any purchasing needs, feel free to contact us at email:Sam.Rui@bjrh-titanium.com