Abstract
An ultrafine-grained (UFG) microstructure in a metastable austenitic CrMnNi steel was achieved using a thermo-mechanically controlled process by rotary swaging and subsequent reversion annealing. The material with an average grain size of 0.7μm was cyclically deformed in total strain controlled tests at strain amplitudes in the range of 0.3%≤Δεt/2≤1.2%. This treatment increased the cyclic stress amplitudes as well as the fatigue life in comparison with the conventionally grained counterpart. For strain amplitudes Δεt/2≥0.4% a martensitic phase transformation occurred, which was observed in situ by a ferrite sensor as an increase of the α′-martensite fraction. The microstructure changes, and the deformation mechanisms in particular, were investigated by means of electron backscatter diffraction, scanning electron microscopy in transmission mode and transmission electron microscopy that revealed the formation of small α′-nuclei which rapidly grew until the entire austenitic grain was transformed.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
