How Titanium Alloy Plates Are Produced: Step-by-Step Process

From Sponge to Plate: An Overview

Titanium alloy plate production is a multi-stage process in which each step determines the final microstructure, mechanical properties and surface quality. The route runs from raw material preparation through melting, casting, forging, rolling, heat treatment, surface conditioning and inspection. This article explains each stage with the parameters that matter to engineers who specify or buy titanium plate.

1. Raw Material Preparation

The process starts with titanium sponge, selected by purity grade, and alloying additions such as aluminum-vanadium master alloy, molybdenum or nickel. The chemical composition and impurity content of the charge must be controlled within tight limits because elements like oxygen, nitrogen and hydrogen have a strong effect on strength and ductility. The blended raw materials are pressed into electrodes, which are then welded together to form the consumable electrode for melting.

2. Melting

Melting is carried out under vacuum to prevent oxidation and gas pickup. Vacuum arc remelting (VAR) is the standard route; high-integrity grades are double- or triple-melted to improve homogeneity and remove volatile impurities. The ingot produced is a chemically uniform, dense cylinder, typically from 500 mm to over 1000 mm in diameter depending on the melt shop.

3. Forging

The ingot is first hot-forged on an open-die press to break down the cast structure. Initial breakdown is carried out well above the beta transus (typically 1150–1200 °C for common alpha-beta alloys), followed by working in the alpha-beta field at lower temperatures to refine the grain. Forging converts the ingot into a slab of the required width and thickness, eliminating casting porosity and closing internal defects.

4. Rolling

The slab is hot-rolled on a plate mill in multiple passes, with the rolling temperature controlled relative to the beta transus of the grade. For example, Ti-6Al-4V (Grade 5) is usually rolled in the alpha-beta field around 950 °C after initial breakdown, while commercially pure grades are rolled at lower temperatures. Intermediate annealing between passes restores workability. The result is a plate with uniform thickness, flatness and a controlled microstructure.

5. Heat Treatment

Heat treatment is used to set the final properties. Annealing removes residual stress and softens the material: CP grades are annealed around 650–760 °C, Grade 5 around 700–790 °C. For alpha-beta alloys, solution treatment and aging can raise strength substantially but reduce ductility, so the temper is chosen to match the application. Heating rate, holding time and cooling rate are all controlled.

6. Surface Conditioning and Finishing

After rolling, the plate is descaled by grinding or pickling, and surface defects are removed by local grinding. Depending on the specification, the plate may be cold-rolled for better surface and flatness, leveled, cut to size, and supplied with pickled, blasted, polished or machined surfaces. Dimensional tolerances follow ASTM B265 or GB/T 3621.

7. Inspection and Certification

Final plates are tested for chemical composition, tensile properties, hardness and, where required, ultrasonic soundness. Mill test certificates to EN 10204 3.1 document the results. Aerospace grades may require additional testing to AMS 4911 or customer specifications.

FAQ

Why is titanium melted under vacuum?

Molten titanium reacts rapidly with oxygen, nitrogen and hydrogen in air, which would embrittle the metal and create inclusions. Vacuum arc remelting eliminates this pickup and also removes volatile impurities, giving a clean, homogeneous ingot.

What is the difference between sheet and plate?

Per ASTM B265, sheet is material less than 4.75 mm (0.187 in) thick, and plate is 4.75 mm and thicker. Both are covered by the same standard but rolling and flattening practices differ.

Which titanium grades are most common for plate?

Commercially pure grades Gr1–Gr4, Ti-6Al-4V (Gr5), Gr7, Gr9, Gr12 and Gr23 (Ti-6Al-4V ELI) cover most industrial demand, from chemical plant to aerospace structure.

Why is annealing needed after rolling?

Rolling work-hardens the material and leaves residual stress. Annealing recrystallizes the deformed structure, restores ductility and stabilizes the properties required by the specification.

How is plate quality verified?

Chemical analysis confirms composition, tensile and hardness tests confirm mechanical properties, and ultrasonic testing detects internal defects such as voids and inclusions. Certificates are issued per EN 10204 3.1.

Can plates be supplied with special surface finishes?

Yes. Pickled, blasted, ground, polished and machined surfaces are available; the finish is chosen according to the corrosion, welding or cosmetic requirements of the application.