Influence of thermomechanical processing on microstructural evolution in near-α alloy IMI834

The effect of processing parameters on the evolution of the microstructural characteristics of IMI834 were examined over the temperature range 950-1125 °C at constant strain rates of 0.001-1 s−1 and true strains up to 1.2. During isothermal deformation, differences in the flow softening behavior were observed for processing in the single-phase beta region, as compared to the two-phase alpha-beta region, which has been related to differences in the structural changes occurring in IMI834. In particular, deformation processing of the alpha-beta structure was observed to work the lamellar alpha structure of the transformed beta grains without recrystallization of either phase, whilst microstructural development in a predominately beta structure resulted in the formation of dynamically recrystallized grains that were necklaced around the deformed and elongated beta phase. For the later case, the variation in the dynamically recrystallized grain size was determined to follow a Zener-Hollomon relationship between a strain rate range 0.001 and 1 s−1.