Microstructural evolution and creep for the superalloy Nimonic 263 with modeling of experimental data|Evoluzione microstrutturale e creep per la superlega Nimonic 263: analisi e modellazione dei dati sperimentali

In the present work the experimental results of creep test on the Nimonic 263 nickel-based superalloy were compared, after conventional heat treatment and over-aging conditions at high temperature (up to 3500 h at 800°C). Such comparison showed that the precipitate coarsening after over-aging affects the first part of the creep curves, with an increasing of minimum creep strain rate and consequent decreasing of time to rupture. For the applied stresses and temperatures, the creep curve analysis indicated that the parameter σλp (σ applied stress, λp interdistance between the γ’ precipitates), is effective to describe the usual wide accelerated state for this kind of alloys. Furthermore, experimental data were used to verify a constitutive equation able to assess and predict the γ’ precipitate coarsening effect and the damage accumulation related to the strain evolution.