Texture and microstructure evolution of Incoloy 800H superalloy during hot rolling and solution treatment

Abstract

In this paper, we have implemented a specific hot rolling and solution treatments on Incoloy 800H to examine the evolution of texture and microstructure during this process. We also focused on the analysis of local misorientation (LM) and grain boundary character distribution through electron backscattered diffraction (EBSD) method. The results showed that the hot-rolled microstructure is mainly composed of elongated grains with typical texture components of B, Cu and S at the mid-layer of plates, while substantial inhomogeneous fine grains can be observed between the deformation grains at the surface-layer showing a combination of R-C and R-Cu components. Following solution treatment, the original deformed grains are fully substituted by the fine recrystallized grains and the grain size increases significantly at higher solution temperatures. An alternant lamellar structure of fine and coarse grains forms along the rolling direction at 1050 °C due to the pinning effect of TiC at fine grains boundaries. Besides, C and G are the dominant texture components after solution treatment. With increasing solution temperature, the overall level of LM and micro-hardness decrease stably and a higher ratio of Σ3:Σ(9 + 27) indicates that Σ3n boundaries proliferation mechanism transforms from “Σ3 regeneration” to “new twinning”.