Grain size dependence of the serrated flow in a nickel based alloy

In this paper, uniaxial tensile tests at a constant strain rate were performed on a nickel based alloy with different grain sizes, and the effect of grain size on serrated flow was studied. The results show that the obvious serration phenomena only occurs in the tensile curves for the large-grained samples (> 1.3 mu m), and the critical plastic strain for the onset of serrations increases with the grain refinement. A large number of slip bands are observed in the deformed samples with relatively large grains rather than fine grains. The analysis reveals that the interaction between slip bands and boundaries is mainly responsible for the serration occurrence, and the mean serration amplitude is closely associated with the density of annealing twin boundary. (C) 2015 Elsevier B.V. All rights reserved.