Uncovering the mechanism of dislocation interaction with nanoscale (<4 nm) interphase precipitates in microalloyed ferritic steels

© 2020, © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. Nanoscale interphase precipitation in microalloyed ferritic steels provides a remarkable (200–400 MPa) strengthening increment, however its origin is unclear. Scanning transmission electron microscopy revealed step formation at the matrix/precipitate interface after both macroscopic uniaxial tension and nanopillar compression testing. Supported by Density Functional Theory modelling, dislocation shearing of nano-sized (<4 >nm) VC precipitates was identified as a strengthening mechanism. The findings suggest the operation of an unusual {001} slip–system in the VC nanoparticles. IMPACT STATEMENT: Shearing of VC nanoparticles by dislocations on a non-traditional slip–system was identified as a strengthening mechanism for steels with nanoparticles.