Titanium alloy forming

Titanium and its alloys offer many advantages over other metals, thanks to their excellent density/mechanical properties/corrosion resistance ratio. However, the cost of these parts is high. This limits their applications to the aerospace sector (aircraft engine disks, certain landing gear, casings, wing elements, etc.). 70% of the market consists of long products intended for stamping or casting after melting; the remaining 30% are mainly flat products for stamping, superplastic inflation, or assembly by welding.

We'll be focusing on the production of titanium alloy shapes using plastic deformation techniques, and introducing techniques requiring the addition of liquid metal, such as casting and welding, which are described in detail elsewhere.

As with other alloy systems, the working properties of titanium alloys are highly dependent on microstructure. So, to obtain the best grade for a given application and optimize mechanical properties, thermomechanical and thermal treatments are always used in the various manufacturing stages. The aim is to obtain not only the final shape of the part, but also the microstructure adapted to the mechanical property specifications.

The aim of this article is therefore to provide potential users of titanium and its alloys with a basic understanding of the manufacture of semi-finished and finished products by forging, rolling, extruding, drawing, superplastic blowing or powder metallurgy.

To this end, the text is divided into four parts. First, titanium metallurgy (phases involved, morphology, etc.) is briefly reviewed, along with dynamic and static microstructural evolutions. Next, the manufacture of semi-finished products is presented. Next, the manufacture of finished products is discussed, followed by an introduction to shaping involving the addition of liquid metal.