Effect of Strain Hardening on Precipitation Kinetics in ATI 718Plus

ATI 718Plus components are manufactured by forging a wrought billet in stages to obtain the desired geometry and microstructure. Parts are then heat treated to optimized proportions of γ’ and η phases. η phase is a plate-like phase that precipitates on the grain boundaries of ATI 718Plus, similar to δ phase in Inconel 718. However, the complete kinetic behaviour of η phase precipitation during forging and heat treatment is still not fully understood. This paper investigates the effects of strain hardening on η phase precipitation kinetics in ATI 718Plus. This is achieved through the use of isothermal hot compression tests and heat treatment. Strain hardening was found to affect the η precipitation kinetics considerably. The results reported are a contribution to a fuller understanding of this important process