Twinning induced nanostructure formation during cryo-deformation

Abstract

In the present work the influence of cryo-rolling to a true strain =2.66 on twinning and formation of ultrafine-grained/nanostructure in commercial-purity titanium and Fe-0.3C- 23Mn-1.5Al TWIP steel was quantified using scanning and transmission electron microscopy. Different influence of twinning on the kinetics of microstructure refinement and nanostructure formation in titanium and steel was revealed. In titanium twin boundaries during deformation transform into arbitrary high-angle grain boundaries thereby promoting the microstructure refinement to a grain/subgrain size of 80 nm. In steel twinning has less pronounced influence on the microstructure refinement. However, very fine grains/subgrains with the size of 30-50 nm was observed in the microstructure after rolling at 77K to a true thickness strain of 2.66. © Published under licence by IOP Publishing Ltd.