Article ID Journal Published Year Pages File Type
1573979 Materials Science and Engineering: A 2015 9 Pages PDF
Abstract
A dense intra-granular dispersion of small secondary Nb(C, N) precipitates in commercial TP347 Nb-stabilized austenitic steel was formed during a short-term hardening heat treatment in the temperature window ΔT=1050-950 °C, starting with isothermal annealing at 1050 °C and followed by continuous cooling from 1050 °C to 950 °C. The precipitates are semi-coherent in cube-on-cube orientation relationship with the austenitic matrix, of characteristic faceted octahedral shape with {111} facets and typically d=15±4.6 nm in size. The experimentally determined volume fraction f=1.4±0.2·10−3 correlates well with thermodynamic calculations. The precipitation gives a significant strengthening of the steel from σy initial~529±42 MPa to σy hardened~703±39 MPa, corresponding to a strength increment Δσy~174 MPa (~33%) in good agreement with the prediction for Orowan strengthening. The present work is relevant to the exploration of the application potential of short term hardening heat treatments for precipitation strengthening austenitic steels.
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Physical Sciences and Engineering Materials Science Materials Science (General)
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