Plastic Processing Technology Of Titanium Alloy Plates, Strips And Foil

Titanium alloy plates, strips and foil are core types of titanium alloy processed materials. Their precision, microstructure and mechanical properties directly determine the service reliability and lifespan of terminal components. Plastic processing is a key link in the preparation of such materials. It realizes the forming and modification of billets into finished products by applying external force to induce plastic deformation of billets while regulating the microstructure and properties synchronously.

 

 

Titanium alloys has allotropic transformation, existing as low-temperature α phase and high-temperature β phase. It affects their plastic processing performance. The α-type titanium alloys have poor plasticity and high deformation resistance, while β-type and α+β-type titanium alloys has excellent plasticity and are easy to form.

 

2.1 Rolling Process: The Core Technology

2.1.1 Hot Rolling Process

As the primary plastic processing method for titanium alloy plates and strips, hot rolling produces cold rolling billets or direct plates. It eliminates casting defects, refines grains, and enhances material density and uniformity.

 

Key control parameters: heating temperature, rolling speed, deformation amount, and post-rolling cooling. For near-α high-temperature titanium alloy foil, cladding welding followed by two-stage soaking rolling and cross rolling is adopted to avoid cracking and simplify production.

 

2.1.2 Cold Rolling Process

Cold rolling uses hot-rolled slabs to produce thin plates and foil via low-temperature multi-pass rolling, reducing thickness, improving precision, strengthening materials through work hardening, refining grains, and enhancing surface roughness.

 

It follows the principle of "multi-pass, small deformation, frequent annealing": single-pass deformation 5%–20%, total deformation 50%–80%; intermediate annealing at 500–700℃ for 30–120 min under vacuum or inert gas to prevent oxidation. High-temperature, high-lubricity lubricants are required to avoid scratching and roll sticking. For ultra-thin foil, cladding pack rolling is used, followed by alkaline pickling to remove cladding and oxide layers.

 

2.1.3 Warm Rolling Process

Between hot and cold rolling, warm rolling combines hot rolling's high plasticity and cold rolling's high precision.

Suitable for low-plasticity α-type titanium alloys and high-precision thin plates, it reduces deformation resistance, decreases defects, and avoids high-temperature oxidation and excessive room-temperature work hardening. Key points: precise temperature control, matched deformation speed, and low-temperature post-rolling annealing to eliminate residual stress and stabilize microstructure.

 

2.2 Extrusion Process

The extrusion process involves applying triaxial compressive stress to the billet through an extrusion die to achieve plastic forming. It enables large-deformation processing and inhibits crack generation, making it suitable for titanium alloys with poor plasticity or plates/strips with special cross-sections. It is divided into direct extrusion and indirect extrusion.

 

The key parameters are as follows: the extrusion temperature is close to that of hot rolling, the extrusion ratio is 5–20, and the speed is 0.1–1 m/s. Glass lubricants are used to protect the surface and reduce deformation resistance. Its efficiency is lower than that of rolling, and it is difficult to mass-produce wide plates and strips. It is mainly used for the preparation of small-batch special specifications or the pretreatment of rolling billets.

 

2.3 Forging Process

The forging process for titanium alloy plates, strips and foil involves applying force to the ingot through a forging press to achieve plastic deformation. It can break coarse grains, eliminate internal defects, and prepare uniform and dense forging billets for subsequent rolling. It is mainly used for the preparation of thick plate billets and is divided into open die forging and closed die forging.

 

The core is to control the forging temperature, deformation amount and speed. Low temperature and excessive deformation should be avoided to prevent cracks. Homogenization annealing is carried out after forging to eliminate stress and stabilize the microstructure.

 

2.4 New Plastic Processing Technologies

Superplastic Forming Process: titanium alloys achieve large-deformation and high-precision forming, and can produce ultra-thin and complex-shaped plates and foil. The deformation is uniform without obvious work hardening, which can prevent cracks, reduce deformation resistance, reduce mold wear, and improve precision and surface quality. It mainly adopts vacuum thermoforming and gas pressure forming.

 

Composite Plastic Forming Process: It combines two or more plastic processing methods and integrates the advantages of each process to achieve efficient and high-precision preparation of titanium alloy plates, strips and foil. The mainstream process is "hot rolling + cold rolling + annealing", which is the core technology for mass production of thin plates and foil, and can obtain products with high precision and excellent performance.

 

There are also forms such as "extrusion + rolling". Accumulative roll bonding can refine grains to produce high-strength and ductile ultra-fine-grained plates and strips. Cladding and pack rolling is suitable for the preparation of near-α high-temperature titanium alloy foil, which can prevent surface cracking, improve efficiency and simplify the process.

 

For more details,please contact us via the Email: Sam.Rui@bjrh-titanium.com