Dynamic and meta-dynamic recrystallization behavior of alloy 718 during high temperature deformation

摘要

Compression tests were carried out on Alloy 718 toinvestigate the microstructure development following dynamicrecrystallization, meta-dynamic recrystallization and grain growth.Tests were performed in the temperature range of 927~1066℃and strain rate range of 5~5×10-4s-1, with true strains up to 0.8.Dynamically recrystallized grain size decreases consistently withincreasing Zener-Hollomon parameter (Z=ε exp(Q/RT)) which isfunction of strain rate and temperature. The extent ofrecrystallization increases with a decrease in Zener-Hollomonparameter due to an increase in the critical strain (εc)corresponding to the initiation of dynamic recrystallization. Thefraction of meta- dynamically recrystallized grain, however,increases with increasing the strain rate from 0.01s-1 to 1s-1 Thispaper outlines the microstructural evolution of Alloy 718 duringthe high temperature deformation.