Mitigating cyclic softening and slip localization in metals for engineering applications (29/04/21)

1 minute read

Speaker and Affliation:

Dr. Ankur Chauhan
Research Scientist
Karlsruhe Institute of Technology (KIT)
Germany

When?

29th April, 2021 (Thursday), 05:00 PM (India Standard Time)

Location

Microsoft Teams Meet-up

Abstract

The Fe-Cr binary alloys are the most promising base for fabricating reduced activation ferritic/martensitic (F/M) steels for structural applications of current nuclear reactors. One important drawback of these steels is a continuous cyclic softening; i.e. they lose strength continuously under strain-controlled cyclic loading. This is mostly attributed to the instability of their tempered martensitic structure. To overcome this shortcoming, a small amount of highly stable nano-oxide particles can be distributed into their matrix in order to form so-called oxide dispersion strengthened (ODS) steels. This not only improves high-temperature tensile properties and creep resistance, but also assists in mitigating undesirable cyclic softening at elevated temperatures. Another critical concern for structural materials that undergo cyclic loading is slip localization. Cyclic slip localization starts early in the fatigue life and manifests in the form of distinct dislocation structures formation such as persistent slip bands (PSBs). PSBs are typically related to the formation of extrusions and intrusions, where fatigue cracks are known nucleate. Taking two complexconcentrated alloys as materials system examples, cyclic slip localization is shown to be mitigated by altering stacking-fault energy. Furthermore, for high temperature applications, oxide dispersion strengthening is also successfully employed

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