An investigation into the mechanistic origin of thermal stability in thermal-microstructural-engineered additively manufactured Inconel 718

An obstacle hindering the applicability of surface modification techniques such as laser peening (LP) in high temperature systems stems from thermally-driven degradation desirable, strain-induced material modifications. Illustrated this work is a novel LP scheme termed plus thermal microstructure engineering (LP + TME) comprised cyclic and addition intermittent 600 °C (0.55Tm) heat treatments designed to impart thermally-stable microstructural modifications additively manufactured (AM) Inconel 718 (In718). Instrumented microindentation uncovered significant sub-surface hardness enhancements exceeding HV following TME, 20% increase over as-built material. High magnitude compressive residual stresses ?310 MPa were also measured 350-h exposure; 25% compared subjected only single shot. Thermal stabilization overall enhancement determined be result formation subgrains, subgrain grain growth regulation through pinning effects, dislocation-precipitate interactions.