Influence of Thermo-mechanical Processing Parameters on Grain Boundary Character Distribution Evolution of Cold-Rolled Ni-Based Superalloy

The influence of thermo-mechanical processing (TMP) parameters on the grain boundary character distribution evolution of cold-rolled Ni-based superalloy was studied. Results show that during annealing treatment, growth accident model is considered to be the main mechanism for the formation of new Sigma 3 boundaries in the static recrystallization (SRX) grains. With increasing the annealing time and temperature, there is more time for grain boundary migration and the grain boundary migration is faster at higher annealing temperatures, which can stimulate the formation of Sigma 3 boundaries by increasing the frequency of growth accidents. In addition, the fraction of Sigma 3 boundaries decreases firstly with increasing the strain, and then increases again. At the strains of 0.1 and 0.7, the fractions of Sigma 3 boundaries reach around 60%, which is related to the well development of large grain -clusters. Besides, the evolution of Sigma 1 boundaries, coherent Sigma 3 boundaries, incoherent Sigma 3 boundaries, Sigma 9 boundaries, Sigma 27 boundaries, and random boundaries were also analyzed.