A NOVEL SOLID-STATE ADDITIVE MANUFACTURING TECHNOLOGY IN SUPPORT OF TURBOMACHINERY SUSTAINMENT

Maintenance, repair, and overhaul activities are necessary and critical, often repeated, operations which occur during the lifecycle of turbomachinery components and assemblies. The ability to extend the life and performance of parts via sustainment type activities currently in service offers a significant and beneficial financial impact for both the manufacturers of these components as well as their end-users. Additive manufacturing not only enables manufacturers the ability to "print" complex geometries in a wide array of materials including metals but, in some instances, also offers a novel opportunity for the repair and overhaul of existing components. The MELD process is quickly becoming an established AM technology which has repeated demonstrated success in additive manufacturing, repair, coating, and joining operations. The MELD process creates fully-dense products with near wrought properties, and reduced distortion, at very high deposition rates. MELD is a solid-state process, which yields parts with superior mechanical properties as compared to those produced by liquid-state metal deposition or spray forming processes. It is an open atmosphere process, allowing for extreme scalability. By the nature of the process all depositions, repairs, and coatings are fully dense and do not require any additional processing for densification such as sintering or HIP. Potential disadvantages include the inability to construct complex, finely featured products. The MELD process is well suited for the fabrication, repair, and overhauling of large-scale components as it is not restricted to space restrictive powder beds or vacuum chambers. In addition, the MELD process carries a lower operating cost (comparable to a CNC mill) and requires less infrastructure than traditional melt-based AM technologies. In this presentation, the MELD process will be explored as a viable method for additive manufacturing, coating, repair, and joining operations. Unique attributes will be considered along with resulting advantages and disadvantages. Specific high-level real-world examples presented will include MELD applications which highlight the repair of a cast non-fusion weldable Mg helicopter gearbox housing, the joining and repair operations of simulated damage (holes and cracks) using 2XXX and 7XXX series aluminum alloys, the application of nickel-based super-alloy coatings on high-strength low alloy steels, and the additive manufacture and repair of titanium alloys.