Thermomechanical response of additively manufactured Inconel 718 during hot torsion tests

Abstract

In this study, we have investigated the microstructural changes during deformation of the SLM samples printed Inconel 718 using hot torsion tests. Prior to thermomechanical testing, the as-built samples are homogenized at 850°C for 2 h in Ar atmosphere followed by air cooling. Hot torsion tests are performed at temperatures of 850, 1000 and 1100°C, and at strain rates of 0.01, 0.1 and 1 s − 1 . It is observed that the dynamic recrystallization mechanism progresses with the evolution of annealing twins which is quanti ed by the increase in % of annealing twins during thermomechanical deformation. It is observed that samples deformed at 850°C for strain rates of 0.01 and 0.1 s − 1 shows brittle like fracture and no dynamic recrystallization. However, the samples deformed at 1000 and 1100°C for strain rates of 0.01, 0.1 and 1 s − 1 shows typical stress strain curves obtained for dynamic recrystallization. It is noted that the peak stress decreases with an increase in the temperature and increases with an increase in the strain rate. Alongside, an activation energy (Q) of 379.62 KJ/mol for SLMed Inconel 718 samples is calculated which agrees with the reported values in the literature for Hot compression tests.