How to Forge Titanium？

The first step in titanium forging is selecting and preparing raw materials—this sets the stage for the final product’s quality. High-purity titanium or titanium alloys (like Ti-6Al-4V, the most widely used titanium alloy for forging) are the preferred options. A common real-world example is forging Ti-6Al-4V ELI (Extra Low Interstitials) for dental implants. This alloy—composed of 90% titanium, 6% aluminum, and 4% vanadium—has lower levels of oxygen (≤0.13%), nitrogen (≤0.015%), carbon (≤0.08%), and iron (≤0.25%). That gives it better ductility and fracture toughness, which are critical for medical use: it can withstand dynamic occlusal forces and reduce the risk of microfractures. Before forging, raw materials must undergo vacuum smelting (at 1600～1800℃) to ensure consistent chemical composition and eliminate impurities like air bubbles or inclusions. After smelting, the titanium is cast into ingots, then cut into standard-sized blanks with a bandsaw or plasma cutting machine (cutting speed: 10～15 mm/min for Ti-6Al-4V). Gas cutting is strictly prohibited—high-temperature oxidation can alter titanium’s chemical properties and impair its performance.

Once the blanks are ready, surface treatment is essential to remove oxide layers, oil stains, or any other contaminants—a key step to avoid forging defects. When titanium is exposed to air, it forms a thin but brittle oxide layer (TiO₂, 2～5 μm thick); leave that on, and it can cause cracking during forging. Blanks are usually sandblasted (sand particle size: 0.1～0.3 mm, pressure: 0.4～0.6 MPa) or ground to achieve a clean, smooth surface (surface roughness Ra ≤ 1.6 μm). What’s more, any surface flaws—like scratches (depth > 0.5 mm), dents, or cracks—must be repaired or the blank discarded. These defects can propagate during forging and lead to forging failure.

Heating is one of the most critical steps in titanium forging, since titanium’s plasticity depends a lot on temperature. The blank is placed in a clean, controlled-atmosphere heating furnace (usually a resistance furnace or induction furnace) to prevent oxidation (protective atmosphere: argon or nitrogen, oxygen content ≤ 50 ppm). Heating temperature varies by titanium alloy: Ti-6Al-4V is heated to 920～980℃, pure titanium (Grade 2) to 850～900℃, and Ti-5Al-2.5Sn to 900～950℃—all below titanium’s phase transition point (1010℃ for Ti-6Al-4V), so the metal keeps a stable structure and good plasticity. Heating time also needs precise control: too short, and the blank won’t heat evenly; too long, and the grain size grows, weakening the forging’s mechanical properties. For most titanium alloys, heating time is based on the blank’s thickness—typically 1 to 2 minutes per millimeter (e.g., a 50mm thick Ti-6Al-4V blank needs 50～100 minutes of heating).

Once the blank reaches the optimal heating temperature, it’s quickly transferred to forging equipment (transfer time ≤ 15 seconds) to minimize heat loss. Titanium cools rapidly (cooling rate: 5～8℃/second at 800～900℃), and a temperature drop will significantly increase its deformation resistance, making titanium forging much harder. Common titanium forging equipment includes hydraulic presses (pressure: 5000～20000 tons for large forgings), hot die forging presses, and forging hammers. A notable real example is Forging Titanium pressure hulls for the Triton 36000 submersible. These hulls required 90mm (9cm) thick Ti-6Al-4V forgings with extremely high sphericity (error ≤ 0.1mm) to withstand the pressure at 11,000 meters below sea level. Manufacturers used a 15,000-ton hydraulic press and precise “multiple light blows” (3～5 blows per fire, forging speed: 0.5～1 m/s) following the multi-fire forging process for deep-sea titanium hulls to shape the titanium into a perfect hemisphere. This approach avoided local overheating and ensured structural integrity. Unlike steel forging, titanium forging requires a “multiple light blows” approach instead of heavy, single strikes. This prevents local overheating (which can coarsen grains or cause cracking) and ensures the metal flows evenly into the mold cavity.

Mold preparation is another key to a successful titanium forging process. Forging molds must be made of high-strength hot work die steel (e.g., H13 or W6Mo5Cr4V2) to withstand high temperatures and pressures. Plus, the mold is preheated to 250～350℃ (for Ti-6Al-4V forging) and kept warm for at least 12 hours before use (holding temperature fluctuation ≤ ±10℃). This reduces the temperature difference between the hot blank and the mold, preventing titanium from sticking and ensuring uniform deformation. The mold cavity also features larger forging drafts (3°～5°) and fillet radii (≥5mm) to facilitate titanium flow—since it’s less fluid than steel.

During forging, operators need to closely monitor the blank’s temperature (real-time monitoring, allowable deviation ±20℃), pressure, and deformation. If the temperature drops too low (below 750℃ for Ti-6Al-4V), the blank may need to be reheated to keep its plasticity. Excess metal, called flash, forms during forging and must be removed with a special trimming die once the forging cools to 400～500℃. This flash removal needs to be done carefully (trimming speed: 2～3 mm/s) to avoid damaging the forging’s surface or changing its dimensions (dimensional deviation ≤ ±0.3mm).

After forging, the titanium component goes through post-forging treatments to boost its mechanical properties and dimensional accuracy—critical for meeting high-end application requirements. First, sandblasting removes any oxide layers formed during forging. For Ti-6Al-4V ELI dental implants, sandblasting is followed by a resorbable blast media (RBM) surface treatment (hydroxyapatite particle size: 50～100 μm, pressure: 0.2～0.3 MPa). This uses hydroxyapatite particles to roughen the surface, which improves biocompatibility, encourages osteoblast adhesion, and enhances implant-to-bone osseointegration—all without leaving residual debris. This practice is backed by clinical research on titanium implant surface modification. Next, heat treatment is done. Unlike steel, heat treatment doesn’t drastically change titanium’s hardness; instead, it optimizes the internal structure, making it tougher and more fatigue-resistant. Typical heat treatment for Ti-6Al-4V involves annealing at 750～800℃ for 1.5 hours, then slow cooling (cooling rate: 50～100℃/hour) to room temperature.

Next comes dimensional correction and shot peening to make sure the forging meets specifications. Shot peening uses high-velocity metal particles (steel shot size: 0.2～0.5 mm, velocity: 60～80 m/s) to bombard the forging’s surface, reducing surface stress (residual stress ≤ -300 MPa) and extending its fatigue life by 30%～50%. Finally, the forging undergoes non-destructive testing (NDT)—like ultrasonic testing (detection accuracy: 0.1mm) or X-ray inspection—to find any internal defects (such as cracks, pores, or inclusions) that aren’t visible to the naked eye. In the production of C919 large aircraft titanium forgings, manufacturers used X-ray CT scanning (in line with the YS/T 1813-2025 standard for titanium porosity measurement) to measure micro-voids (porosity ≤ 0.5%) and ensure no internal defects. This helped localize over 100 key load-bearing titanium forgings and break foreign technical monopolies. Only forgings that pass NDT are considered qualified and ready for use.