J. Boykin, R. Shealy
REM Surface Engineering,
United States
Keywords: additive manufacturing, stainless steel, postprocessing, surface finishing
Summary:
Metal Additive Manufacturing (AM) offers many potential benefits to the Air Force (USAF). AM can greatly reduce manufacturing lead-time on legacy components, helping to meet readiness and sustainment goals. However, AM surfaces have high surface roughness values that do not meet part specifications. Many USAF legacy components have complex geometries, not easily machined or otherwise surface finished. REM Surface Engineering’s (REM) process technology has shown the ability to solve AM component roughness challenges on complex geometries, but currently, parts require largely individual process development to understand required surface material removal and shape offsets. This effort is generating a material offset guide for AM Stainless Steel alloy components (17-4, 15-5, 316L) for use in association with the developed optimal surface finishing processes which will enable the Air Force to generate ready to use AM components without requiring complex machining operations. Additionally, REM will generate corresponding fatigue data at various roughness targets achieved via the application of the optimal surface finishing processes. Lastly, REM will investigate the effect of various printing/heat treatment approaches (contour scanning, hot isostatic pressing, and support removal) to identify for the Air Force optimal approaches for varying part performance requirements while targeting minimized manufacturing lead-time and costs. Metal additive manufacturing is revolutionizing manufacturing via the reduction of operational steps, component lead time, and component cost. Of particular interest to the aviation industry is the manufacturing of legacy components to address sustainment and readiness challenges associated with a dwindling supply base, high costs, and long lead times. These capabilities make AM an important technology for the US Air Force and industry; however, the AM process has inherent challenges that hinder full implementation. Namely, the detrimental effect of surface texture and surface-related defects on the component’s mechanical properties and generally high starting roughness values they create, which prevent simple “like for like” component adoption. SRDs reduce the mechanical strength and dynamic performance of AM components, making them unreliable for critical applications. The proposed development of optimal process parameters, manufacturing and heat treatment recommendations, and material offset requirements guides for AM Stainless Steel Alloy (SSA) components would improve and increase the availability of necessary spare parts and the reliability of AM SSA parts. With such, industry will see a decrease in spare part lead times and costs while realizing an increase in operational availability and component material properties.