Investigation of post-heat treatment on precipitation kinetics and mechanical properties Inconel 718 superalloy additively manufactured by selective laser melting

This scholarly article delves into the impact of diverse heat treatment protocols on the microstructure and mechanical characteristics of Inconel 718 alloy fabricated via selective laser melting (SLM). By elucidating the dissolution transformation dynamics of the elongated chain-like Laves phase and the honeycomb-like network structure during heat treatment, The investigation primarily aims to clarify the precipitation size and the microscopic formation mechanism of the & ouml; and gamma '/gamma '' phase enhancement following solution annealing (SAT) and homogenization annealing treatment (HAT). SAT yielded needle-like & ouml; phase with particle dimensions spanning from 1 mu m to 1.5 mu m, whereas HAT resulted in the formation of nanoscale spherical precipitates of gamma '/gamma ''. Concurrently, the study takes into account the anisotropy of the various construction surfaces of the samples, conducting microhardness, tensile strength, and fracture analyses. These analyses demonstrate that heat treatment imparts varying degrees of enhancement to the mechanical properties of the SLMed 718 superalloy. Notably, the SAT group boasts the highest hardness, peaking at 513HV, albeit with a concomitant reduction in ductility. The tensile strength of the HAT group experiences a marked increase, reaching 1038 MPa, but the hardness increases least. These findings not only lay the groundwork for a more profound comprehension of the anisotropy disparities within additive manufacturing but also offer a pragmatic framework for the rational design of heat treatment protocols for laser additive manufacturing of nickel-based superalloys.