Publication

Materials & Advanced Manufacturing (MAM)
2018

ADDITIVE MANUFACTURING REPAIR METHODS FOR METALLIC COMPONENTS

by Kenneth M. Sabo; Brock T. Golesich; Michael L. Tims

Abstract

As metallic parts are used, wear, fracture, galling, warpage, and other forms of obsolescence occur. When these issues progress beyond a predefined level, the parts are either replaced or repaired. Replacement leads to undesirable logistics requirements, especially for those parts requiring difficult-to-source, expensive and/or long-lead-time materials. Repair options are often limited due to strict performance requirements of the parts or concern over the quality of the repair. Two relatively new additive manufacturing (AM) process options exist to complete repairs, including repairs required in theater. Hybrid repair via metal AM followed by precision machining within a single setup offers unique repair options not previously available. Though somewhat limited with respect to the number of alloys currently tested, hybrid AM via directed energy deposition (i.e., powder sprayed into a laser-heated liquid metal pool) offers the possibility to quickly, economically and accurately repair metallic components without the side effects associated with more common methods including traditional weld repair. Another repair method gaining acceptance in the DoD community is cold spray. Here a metal powder is accelerated to supersonic speeds and aimed at a metal substrate forming craters that help the newly added metal to adhere. In addition, atomic diffusion occurs between added particles resulting in further adhesion of the added metal. These AM processes generally lack qualification standards for use in repair of DoD applications. But, the nature of repair and the buildup of material(s) should be much faster to reach qualification status, even if itís on a part-by-part, or application-specific basis. This paper defines hybrid AM and cold-spray technologies relative to repair of metallic components of interest to the DoD. The state of the art is discussed and several examples of the use of the equipment are presented. Hybrid builds of Inconel 718 features onto preexisting substrates are discussed. Mechanical properties of the build material are presented. Finally, a plan for use of these technologies by the DoD is defined.