Addressing Scalability and Surface Related Defects of Additively Manufactured Nickle-Based Superalloy Components

R. Shealy
United States

Keywords: additive manufacturing, nickel-based alloys, surface finishing


Additive Manufacturing (AM) is an exciting frontier that shows promise for ushering in a new era of efficient manufacturing and production across nearly every industry, including the rigorous standards for commercial and federal aerospace applications. As with any new technology, AM is inherently filled with “opportunities for innovation.” Some “opportunities” are universal across AM alloys and superalloys. In order to activate the full potential of AM, REM is addressing issues which can occur regardless of printing technique. REM Surface Engineering, founded in 1965, has been a leading provider of isotropic superfinishing services in traditional industries for decades. We have recently adapted our existing technologies and developed new technologies to create a superfinishing process capable of remediating all surface and near surface defects on AM components. In a process which combines unique proprietary chemical polishing and chemical/mechanical polishing, we are able to remediate all surface defects, as well as near surface defects, as well as polish internal channels/non-line-of-sight surfaces (something which traditional processes such as machining cannot accomplish). Furthermore, the process has been proven to increase fatigue life and performance over as-printed parts. Since being awarded our first Phase I NASA SBIR contract in 2018, REM has received over $4.5 million in federal funding to adapt this process for NASA Marshall and NASA JPL’s unique needs, including alloys printed in Inconel 625, Inconel 718, NASA HR-1, GrCOP-42, GrCOP-84, JBK-75, and is currently in development for the U.S. Air Force in alloys Al-6061-RAM2, Scalmalloy, A7050, Ti-6Al-4V, and F357 and develop guidelines for the production of high-use IN-718 AM components. This presentation highlights ongoing REM efforts to tailor proprietary chemistries and processes for alloys and superalloys of interest to federal agencies and commercial manufacturing, specifically the increasing need to scale the size of components capable of being surface finished. Surface and near-surface defects, such as roughness/waviness, porosity, or partially sintered metallic powder, are remediated by controlled material removal to yield smooth planarized surfaces. This extends to modification of internal cavity surfaces as well, provided the cavity is accessible. For example complex coolant passages can be incorporated into the walls of firing chambers or rocket nozzles without the lingering burden of imperfections which can create an environment for crevice corrosion or FOD. Due to the demonstrated success of the base Phase II effort, REM’s capability has increased from 6”x6”x6” to 30”x30”x24” (Figure 1) and subsequent successful hot fire testing of a finished nozzle (Figure 2), a Phase II-Extended effort was awarded with the goal of further increasing processing capability to 60”diameter x 72” length nozzle-like nickel-based superalloy components.