Cold Working and Annealing Effects on the Creep and Rupture Resistance of the Oxide-Dispersion-Strengthened Alloy MA754

The mechanisms of the deformation and annealing response of MA754 were examined through a study of the inter-relationships between cold work and thermal treatments as they affect various material performance parameters at elevated temperatures. Various cold rolling plus annealing experiments indicate that the recrystallization of MA754 is controlled by primary recrystallization principles. It has been found that, through the application of a stepwise cold rolling plus annealing schedule, total reductions of at least 40% (reduction in thickness) at ambient temperature can be obtained while at the same time maintaining a grain morphology favorable for good high temperature properties. High temperature (0.94 T sub m) annealing treatments given to stabilize the grain structure following cold work produce a change in both the size and distribution of the dispersoid phase. Measurements reveal that the average particle size increases as (time), typical of diffusion-controlled Ostwald ripening. The coarsening observed in the process material is restricted to the grain boundaries, and results in a significant loss in creep resistance.