Low-strains high temperature annealing effect on the grain boundary character distributions and the grain boundary plane distributions of Hastelloy C-276

Abstract:

Hastelloy C-276 was solution-treated at 1150℃ for 30min, after that, the samples were subjected to cold rolling with different reductions and annealing at high temperature. The grain boundary character distribution(GBCD) and the grain boundary plane distribution were characterized by electron backscatter diffraction (EBSD) technique. The results shown the fraction of Σ1 boundary was decreasing during annealing process. Meanwhile, the fraction of Σ9 boundary and Σ27 boundary was increasing. This is due to the stored energy was exposed to the migration of grain boundaries and promoting the interaction of grain boundaries. While grain size grew up abnormally during heat treatment, that led to the formation of special boundary. The special boundaries disrupted the connectivity of high angle boundaries. After the low-strains higher temperature annealing process, Σ3 boundaries with the {111} plane were twist boundaries and Σ9 boundaries with the [110] zone were tilt boundaries. Under different deformation conditions, the distribution of Σ3 grain boundary plane was different from Σ9 grain boundary plane, due to the proportion of Σ3 grain boundaries was different and the interactions of special boundaries were occurred.

Key words:Hastelloy C-276; Grain boundary character distributions; Grain boundary plane distributions; Thermomechanical processing