Effect of Delta Phase on the Hot Deformation Behaviour and Microstructural Evolution of Inconel 718
In order to investigate the influence of -phase precipitation during high temperature forging of Inconel 718, hot axi-symmetric compression tests have been performed on specimens with two distinct initial microstructures: i) as-received material containing a dense population of precipates at grain boundaries and along intragranular slip planes, and ii) material solution-treated to dissolve the phase. Results indicate that the presence of leads to a slight increase in peak stress and a proportionately greater post-peak reduction in flow stress, as compared to solution-treated material. For both types of microstructure flow softening is associated with grain refinement, but in different ways: in -free material conventional dynamic recrystallisation leads to the formation of new grains, whereas the presence of plate-like appears to cause the mechanical break-up and segmentation of prior grains.
T. Chandra, N. Wanderka, W. Reimers , M. Ionescu
H. M. Lalvani et al., "Effect of Delta Phase on the Hot Deformation Behaviour and Microstructural Evolution of Inconel 718", Advanced Materials Research, Vols. 89-91, pp. 313-318, 2010