Microstructural Refinement of As-Cast Alloy 718 Via Thermomechanical Processing

Abstract

Technology demand for improved tensile and fatigue properties in the final components requires Alloy 718 producers to develop a fine grain practice for the cogged billet derived from the ingot. The effect of thermomechanical processing on the microstructural refinement of Alloy 718 was studied. The results of this study revealed that under certain thermomechanical processing conditions, substantial microstructural refinement can be obtained. Large portion of the softening associated with the recrystallization process did not occur by the formation of new, strain free grains via the motion of high angle boundaries, but rather, by the formation of dislocation free annealing twins that grow directly into the deformed matrix.