Abstract Scope |
Isotropic/scalar work hardening is well understood in concept: plastic deformation induces dislocation multiplication and intersection, with strengthening by higher dislocation density and shorter pin spacing. Directional/tensor metal memory has no simple microstructural interpretation. Manifestations include the Bauschinger effect, ratcheting in fatigue, back stress in creep, and anelasticity.
Recent experiments and simulations suggest that anelasticity and other tensor memory effects are the result of the concurrent operation of two mechanisms: 1) development of internal stress by GND evolution and 2) bowout of dislocation segments. Evidence for this hypothesis will be summarized, new and from the literature. Experimental and simulations show that directional hardening is likely significant at all length scales and for all metals. Predictions are compared with measurements.
Major References:
Dayong Li and Robert H. Wagoner: The Nature of Yielding and Anelasticity in Metals, Acta Materialia, 2021, 206, doi 116625.
G. Zhou, W. Jeong, E.R. Homer, D.T. Fullwood, M.G. Lee, J.H. Kim, H. Lim, H. Zbib, R.H. Wagoner: A predictive strain-gradient model with no undetermined constants or length scales, J. Mech. Phys. Solids, 2020, 145, doi 104178. |