Failure of a laser powder bed fusion fabricated GH3536 superalloy reverse-flow combustor flame tube under near-service conditions

• First study on the failure of a laser powder bed fusion fabricated GH3536 superalloy reverse-flow combustor flame tube under near-service conditions. • Analysis of the reasons contributing to distinct crack modes at the primary hole edge and inter-hole area. • Corrosion pits on the inner wall surface act as initiation sites for cracks. • Multi-scale characterizations reveal grain boundaries as preferential paths for oxidation and sulfidation. • Fatigue-creep, oxidation and hot corrosion synergistically accelerate crack initiation and propagation. Additive manufacturing (AM), as a disruptive technology, has been increasingly applied in the aerospace industry due to its unique advantages in fabricating complex and precise parts. However, systematic investigations into the failure mechanisms of AM-fabricated aerospace parts under service conditions remain limited. This study investigates the failure mechanisms of an AM-fabricated GH3536 superalloy reverse-flow combustor flame tube subjected to near-service conditions. Results show that cracking on the inner wall surface of the flame tube is dominated by the synergistic effects of fatigue-creep, oxidation and hot corrosion, occurring predominantly in an intergranular mode with partial transgranular features. Corrosion behavior is characterized by a porous and heterogeneous corrosion layer, intergranular oxidation and sulfidation, and the formation of corrosion pits. At the primary hole edge, intragranular corrosion pits initiate transgranular cracks, which transition into intergranular propagation toward the inter-hole area, where corrosion products and pits along grain boundaries further facilitate the initiation and propagation of intergranular cracks.