As our second in a series of “Forging Process Innovations” blog posts, we’ll look at the application of forging preforms that are made using Powder Metallurgy and Additive Manufacturing processes. Unlike traditional manufacturing processes that produce shapes by taking material away, Additive manufacturing (AM) creates 3-dimensional structures by adding thousands of layers which combine to create a net shape or near-net shape. For metal part manufacturing, the AM process uses Powder Metallurgy or wire somewhat like MIG welding, typically with electron beam, laser-based sintering or fusion for deposition of metallic layers.

While Powder Metallurgy (PM) manufacturing processes have become increasingly common for production of non-structural metal components, inherent voids and microstructural discontinuities from the PM and “welding” processes can be a limiting factor for attaining strength and durability needed in critical structural components. The use of AM in making forging preforms combines the flexibility and efficiency of near-net-shape manufacturing with the strength and durability properties of wrought manufacturing processes.

The controlled deformation of the forging process removes porosity and voids in the PM preforms, also adding directional properties for strength, ductility, and resistance to impact and fatigue that wouldn’t be possible with AM alone. In many alloys, deformation energies help drive dynamic recrystallization in subsequent thermal treatment.

Successful PM/AM Preform Forging Applications
This preforming process has been used successfully by Federal-Mogul to manufacture steel connecting rods and brackets in “green form”, with the forging process used to densify and improve mechanical properties. Arconic is also using AM preforms to manufacture titanium wing spars. Through powder blends of preforms, the subsequent forging process is reducing component input weight by one half to two thirds for critical structural aerospace components.

Other non-ferrous uses of powder metallurgy or additive manufactured preforms include aluminum applications, where forging is a faster alternative to Hot Isostatic Pressing to achieve reduced porosity, increased density, and true wrought properties in aluminum metallurgy.

QC Forge Impeller Preform Development
QCF is currently actively involved with PM manufacturers in the development preform processes for forging larger aluminum impellers that were previous manufactured in steels. For use in both cold and hot side turbocharger applications, this forging innovation promises reductions in both weight and cost of impellers used in microturbine power generation systems or small aero engines.