Effect of heat treatment conditions on the plastic deformation behavior of the Inconel 706 alloy

Although the Inconel 706 alloy has been developed to reduce the manufacturing cost for mass production, the effect of post-heat treatment on the deformation mechanisms of this alloy system has not been well investigated yet. In this study, the effect of heat treatment conditions on the plastic deformation behavior of the Inconel 706 alloy was analyzed. The size of the coherent γ'/γ'' co-precipitates in the sample subjected to 3-step aging (3STEP) is larger than that in the sample subjected to 2-step aging (2STEP). However, the yield strength of 3STEP is lower than that of 2STEP due to the precipitate-free zone near its η phase which reduces the volume fraction of the γ'/γ'' co-precipitates. The coarsened η phase in 3STEP also acts as a crack initiation site, inducing intergranular fracture. Meanwhile, serrated flows were observed in the tensile stress-strain curve of 2STEP tested at a high temperature condition, which resulted in ductility degradation. The present result indicates that the different heat treatment conditions for the Inconel 706 alloy affect the morphology of the precipitate in the matrix, which can be attributed to their deformation behaviors.