Abstract
Nanocrystalline austenite having fully annealed and equiaxed morphology, grain sizes varying from 400 nm to 1.7 µm, and a large fraction of high-angle grain boundaries was prepared in Fe–24Ni–0.3C (mass%) alloy by high-pressure torsion and subsequent heat treatment. The nanostructures were formed through reverse transformation of deformation-induced martensite and recovery/recrystallization of retained austenite. The austenitic grain size decreased with increasing shear strain below the strain of 50, while it increased above the shear strain of 50 due to decreased austenite-transformation starting temperature.
