Post-processing treatments–microstructure–performance interrelationship of metal additive manufactured aerospace alloys: A review

The application of Metal Additive Manufacturing (MAM) in the aerospace industry has been gaining attention. The poor surface quality of parts greatly limits the prospects of MAM-produced parts in the aerospace industry as fatigue performance hinges on a good surface finish and homogeneous microstructure. Post-processing treatments are important to improve the surface quality and the overall performance of MAM-produced parts during static and dynamic loadings. This paper provides a review of the current state of post-processing treatment options for MAM-produced parts. The advances in the post-processing treatments of MAM parts to improve fatigue strength, tensile strength, surface integrity and other properties of parts are reviewed. Future research prospects on metal additive manufacturing of aerospace parts are briefly expounded. Abbreviations: AM: Additive Manufacturing; CMT-WAAM: Cold Metal Transfer-Based Wire Arc Additive Manufacturing; CSD: Cold Spray Deposition; DA: Direct Aging; DED: Directed Energy Deposition; E: Elongation; EBAM: Wire-feed Electron Beam Additive Manufacturing; EBAM Electron Beam Additive Manufacturing; EBSD: Electron Back Scattered Diffraction; FRAM: Friction Rolling Additive Manufacturing; FSAM: Friction Stir Additive Manufacturing; FSP: Friction Stir Processing; HFDB: Hybrid Friction Diffusion Bonding; HIP: Hot Isostatic Pressing; HSA Homogenisation + Solution Treatment + Aging; IFSP: Interlayer Friction Stir Processing; IPF: Inverse Pole Figure; KAM: Kernel Average Misorientation; LAM: Laser Additive Manufacturing Process; LENS: Laser Engineered Net Shaping; LDM: Laser Deposition Manufacturing; L-PBF: Laser Powder Bed Fusion; MAM: Metal Additive Manufacturing; MTFS: Multi-track Multi-layer Friction Surfacing; O-WLAM: Wire Oscillating Laser Additive Manufacturing (O-WLAM); S: Solution Treatment; SA: Solution Treatment + aging; TEM: Transmission Electron Microscope; UAM: Ultrasonic Additive Manufacturing; UTS: Ultimate Tensile Strength; WAAM: Wire Arc Additive Manufacturing; YS: Yield Strength