| Abstract Scope |
Additive manufacturing (AM) is gaining momentum for producing high-performance, load-bearing components in critical industries such as oil and gas and energy. Nickel-based superalloys, known for their strength and corrosion resistance, are well-suited for extreme environments, however, their adoption via AM, particularly for safety-critical applications, demands robust qualification frameworks to address the unique microstructural and performance challenges introduced by layer-wise fabrication.
This study presents a qualification methodology for laser powder bed fusion (PBF) of nickel-based superalloys, using UNS N07718 as a representative material. The approach comprises two phases: (1) a Design Phase, involving metallurgical and mechanical characterization to validate material integrity, and (2) a Performance Phase, assessing resistance to environmental cracking under simulated field conditions.
Mechanical testing in the Design Phase included tensile, hardness, and impact evaluations, alongside chemical verification and microstructural analysis to ensure compliance with required industry standards. In the Performance Phase, slow strain rate testing (SSRT) and high-pressure, high-temperature (HPHT) C-ring tests were performed to evaluate resistance to hydrogen embrittlement and stress corrosion cracking in H2S containing service environments.
Results show that microstructural characteristics, shaped by AM process parameters and powder properties, significantly influence environmental performance. Variability in cracking resistance underscores the need for controlled processing and application-specific testing.
This work outlines a rigorous path toward qualifying AM-produced nickel-based superalloy components for demanding applications and provides a framework adaptable to other alloys and environments. |