As an aerospace and energy component, IN718 is a typical superalloy. Its high strength and hardness, combined with its resistance to surface corrosion and embrittlement at high temperatures, make it a suitable candidate for applications in high-temperature environments. However, its poor machinability presents some challenges for conventional manufacturing. Moreover, there are few studies on the elevated-temperature mechanical behavior of IN718. Therefore, the current work aims to investigate the effects of different thermal post-treatment conditions on AM IN718.
First, the influence of the heat treatment on the microstructure of the AM IN718 is investigated. Specifically, the grain morphology and phase structure of the g-matrix of the alloy are studied. The results show that the evolution of these properties is determined by the heat treatment conditions. In addition, the effect of solution treatment time and homogenization time is also investigated.
During heating, a local liquid film forms on the grain boundaries, which solidifies during cooling down. This can increase the geometric complexity of the components. Moreover, it can reduce the ductility of the alloy. To counteract this, the specimens were preloaded with 50 N, so as to prevent the sample from buckling during heating.
Heat treatment increases the tensile strength of the alloy. On the other hand, it also decreases the elongation to failure. Further investigations are required to determine the dominant mechanism responsible for these changes.
A study of recrystallization was performed by J. Chen. The result shows that the duration of the solution treatment and the time of the homogenization have a significant effect on the strength of the material.
