Microstructure and Tensile Properties of In718 Superalloy Aged with Temperature/Stress Coupled Field

The microstructures and tensile properties of the IN718 superalloy aged with and without stress were investigated. The results showed that in the temperature/stress coupled field, the coarsening of the y00 phase and precipitation of the 8 phase in the alloy were signifi-cantly accelerated. The alloys aged with stress showed lower strength and plasticity compared to those without stress, indicating that the degradation of the tensile properties was accelerated by the applied stress when aging, and such degradation was explained as follows. The accelerated coarsening and quantity reduction of the y00 phase was caused by the coupled effect of temperature and stress. This weakens the strengthening effect of the y00 phase on the alloy and the ability to capture and accumulate dislocations. When many needle-like 8 phases precipitated near the grain boundaries, many micro-cracks formed, propagated rapidly, and connected along the zones without y00 phases. Such microcrack propagation was unstable, resulting in plastic deformation localization. (c) 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).