Metal Additive Manufacturing (MAM) for Critical Aerospace and Defense Components

Additive Manufacturing, known as 3D Printing or Direct Manufacturing, has become the leading edge manufacturing technology. Today Metal Additive Manufacturing (MAM) is a reality, not only for prototype fabrication, also for functional parts in various industries. As the industry progresses towards implementing AM in more critical parts, new material and process innovation are imperative. Besides material development, there are opportunities for manufacturing critical, in particular fracture and fatigue critical parts taking advantage of the ultrafine microstructure that is common in all metal AM processes. This presentation will show the results of such an effort in which the ultrafine grain microstructure is retained while breaking down the micro-inhomogeneity arising from elemental partitioning during solidification in all fusion based metal AM processes. Current investigation shows how a forging preform can be designed with tailored stain distribution to recrystallize fine grains and impart grain flow during the forging resulting in high strength, fracture toughness, and fatigue properties that are essential in fracture and fatigue critical parts in aerospace and defense applications. The presentation will show the minimum strain required in AM 316 stainless steel and Ni Alloy 718 to recrystallize strain free fine grain and chemically homogenous microstructure during forging. The presentation will also show the forging preform design based on this minimum strain in the center and maximum strain required to generate grain flow on the outer envelope of the forging. The results of this investigation will include both PBFLB and DED (WAMM) based forging preform design and forging performance to illustrate the path for manufacturing AM based fracture and fatigue critical for Aerospace and Defense Industry.