The Additive Manufacturing (AM) of Alloy 718 oilfield components by Powder Bed Fusion - Laser (PBF-L) is attractive from lead-time and sustainability standpoints. For this investigation, AM 718 coupons built by PBF-L were acquired from four AM commercial providers. Powder composition, post-processes, microstructures, and mechanical properties of AM 718 were evaluated using standardized test coupons. Resistance to sulfide-stress-cracking (SSC) was measured using (a) NACE TM0177 Method A and Method C tests in NACE MR0175 Level III (including with galvanic coupling) and Level VII conditions and (b) slow-strain-rate tests (SSRT) per NACE TM0198 in a Level VII environment. Also, with the collected dataset, the cracking resistance and failure mechanisms of AM 718 in sour environments were compared against its wrought counterpart from API Specification 6ACRA 718. Through new test results, this paper discusses the important parameters that optimize AM 718 for further Oil & Gas utilization and determines that the variability in AM 718 properties can be managed, overcome, and optimally meet the API Specification 6A CRA minimum requirements with the proper processing route.
Over the past twenty years, additive manufacturing (AM) has gradually emerged as an important commercial manufacturing technology for the production of components, particularly complex and high-value metallic components. AM enables the layer-by-layer rapid manufacturing of near-net shapes using 3D computer-aided design data and typically minimizes raw-material wastes. Rapid progresses in AM metal processing, including lower cost and reliable industrial lasers, more affordable and available powder feedstocks, higher performance computing, improved non-destructive testing, have all transformed AM to a primary manufacturing solution in multiple industrial sectors.1,2 Over the years, there have been major strides to better understand the influence of AM processes on the mechanical properties, microstructures, and corrosion performances of AM products, yet AM is still not well understood and controlled for some applications. Partly due to different process routes, the corrosion performance of AM alloys is frequently not matching the performance of their wrought counterparts. The corrosion of AM materials is influenced by the manufacturing process and its parameters: these influence porosity, grain structures, residual stresses, solute segregation, surface roughness, among others.3,4
