The Whole‑Process Precision Die Forging Of Titanium Alloys

Precision die forging of titanium alloys is an efficient near‑net‑shape forming process. It addresses the pain points of difficult‑to‑machine properties and low material utilization of  titanium alloys, reduces machining allowances, and improves the dimensional accuracy and mechanical‑property stability of parts. Compared with conventional forging, this process imposes stricter control requirements on temperature, dies, deformation parameters, lubrication and protection. The full‑process process level directly determines the quality and service reliability of forgings.

1. Raw Materials and Billet Pretreatment

Three‑time VAR (Vacuum Arc Remelting) are adopted. Strict control is exercised over vacuum degree, melting rate, chemical composition and oxygen content to eliminate internal defects. Billets are precisely saw‑cut, ground and pickled to remove surface defects. Uniform and fine original grains are required to guarantee stable microstructure of forgings.

2. Die Design and Pretreatment

High‑temperature‑resistant and wear‑resistant hot‑work die steel is selected. The die cavity is designed with a draft angle of 3°‑5° and fillet radii no less than 5 mm, and the cavity surface is finish‑ground. Dies are preheated to 250‑350 °C. Cavity geometry and die‑closing clearance are verified before production to avoid die sticking, cold‑shock cracking and filling defects.

3. Equipment Selection

High‑precision hydraulic presses of 2500 t or above are deployed, with a pressing speed of 50‑100 mm/s and wall‑thickness deviation of forgings ≤ 1 mm. Online monitoring of pressure, displacement and temperature is equipped to realize closed‑loop control of process parameters and ensure stable accuracy of mass‑produced forgings.

1. Heating Temperature Control

Segmented forging is performed according to the phase‑transformation characteristics of titanium alloys: cogging is carried out in the β‑phase region to break coarse β grains; finish forging is completed in the α+β two‑phase region to balance plasticity and microstructure‑related properties and restrain grain coarsening and toughness deterioration. Billet temperature fluctuation is controlled within ±20 °C to prevent overheating or insufficient heating.

2. Heating‑up and Holding Procedures

A multi‑stage slow heating‑up scheme is applied to avoid billet cracking induced by thermal‑gradient stress. After reaching the forging temperature, billets are held according to their thickness for uniform through‑thickness temperature and softening. Oxidation‑free heating under vacuum or inert‑atmosphere conditions is adopted to mitigate oxidation and hydrogen absorption, so as to prevent alpha case layers from impairing forging accuracy and corrosion resistance.

1. Multi‑stage Forging Deformation Strategy

A three‑step forming mode of "light‑blow preforming - heavy‑blow cavity filling - pressure‑holding sizing" is adopted to compact pores and ensure densification and dimensional accuracy. Multi‑heat forging is applied for special‑shaped thick‑walled components. The deformation per heat ranges from 50 % to 80 %, and the total deformation exceeds 70 %. Intermediate annealing is implemented to refine grains and relieve stress. Conventional precision forgings realize near‑net‑shape forming with tolerances ≤ 0.1 mm and reduced machining allowances.

2. High‑temperature Lubrication and Anti‑sticking Technology

Titanium alloys tend to stick to dies at high temperatures. Water‑based graphite or glass lubricants are used to form isolating films on billet and die surfaces, which reduce friction, improve metal flow, mitigate surface scuffing and die wear, and slow down billet temperature drop. Uniform coating thickness is required to avoid dimensional defects caused by lubricant accumulation.

3. Dynamic Monitoring during Forming

Forging temperature, pressure, pressing speed and displacement are monitored throughout the process. Forging shall be terminated when the temperature of Gr5 billets drops below 750 °C to prevent low‑temperature cracking and microstructure degradation. Defects such as insufficient material, folding and flash are inspected in real time, and parameters are dynamically adjusted to stabilize mass‑production quality.

1. Graded Cooling Control

Differentiated cooling regimes are applied to forgings and dies: the die cooling rate shall not exceed 20 °C/h; dies are held at 600 °C for 4 h and slowly cooled to below 200 °C before die opening, so as to prevent thermal cracking and deformation and extend die service life. Forgings undergo controlled air cooling at a cooling rate of 5‑10 °C/min. This avoids residual stress from rapid cooling as well as grain coarsening and strength degradation due to excessive slow cooling.

2. Precision Heat‑treatment Procedures

Forgings are subjected to vacuum annealing to eliminate forging‑induced residual stress, homogenize and refine microstructure, and optimize strength‑plasticity‑toughness performance. For high‑load components such as aerospace disk parts, solution and aging treatment is added to enhance strength, hardness and fatigue performance. Oxide scale and residual lubricants are removed after heat treatment to facilitate subsequent machining and surface treatment.

Ruihang has the largest storages of Titanium & Titaniums products in Baoji area. The details for industrial & aerospace buyers,engineers and procurement needs, please feel free to contact us via email:Sam.Rui@bjrh-titanium.com