Subgrain and dislocation structure changes in hot-deformed high-temperature Fe–Ni austenitic alloy

The influence of plastic deformation on the substructure of a high-temperature austenitic Fe–Ni alloy has been presented. Hot-torsion tests were executed at constant strain rates of 0.1 and 1.0s−1, at testing temperatures in the range 900–1150°C. The examination of the microstructure was carried out, using transmission electron microscopy. Direct measurements on the micrographs allowed the calculation of structural parameters: the average subgrain area, and the mean dislocation density. A detailed investigation has shown that the microstructure is inhomogeneous, consisting of dense dislocation walls, subgrains and recrystallized regions.