Modeling the effects of morphological anisotropy in transformation plasticity of metals and alloys

• Published in: International journal of solids and structures 2023-10, Vol.282, p.112447, Article 112447
• Main Authors: El Majaty, Youssri, Tran, Le-Hung, Leblond, Jean-Baptiste, Brenner, Renald
• Format: Article
• Language: English
• Subjects: FFT micromechanical simulations; Greenwood–Johnson’s mechanism; Limit-analysis; Mechanics; Mechanics of materials; Morphological anisotropies; Physics; Solid mechanics; Transformation plasticity
• ISSN: 0020-7683; 1879-2146
• DOI: 10.1016/j.ijsolstr.2023.112447

There has recently been renewed interest in the theoretical modeling of Greenwood and Johnson (1965)’s mechanism of transformation plasticity of metals and alloys. Neglecting the effects of elasticity and using an analogy with problems of ductile rupture, El Majaty et al. (2018) transposed to transformation plasticity the powerful methods of limit-analysis usually applied to plastic porous materials, by replacing empty voids through nuclei of daughter-phase expanding within a shrinking matrix of mother-phase. Their work, based on the hypothesis of spherical growth of nuclei of daughter-phase implying overall geometric isotropy, disregarded the frequently observed effects of morphological anisotropies. The present study introduces these effects by extending El Majaty et al. (2018)’s limit-analysis-based approach to spheroidal, instead of spherical, nuclei of daughter-phase. A typical consequence of the morphological anisotropy thus introduced is the prediction of a nonzero transformation plastic strain even in the absence of any external stress applied. The theory is completed by FFT-based numerical simulations. While essentially confirming the theory, these simulations suggest to overhaul it through heuristic corrections of the expression of the transformation plastic strain rate, accounting for the presence and influence of elasticity. •A model of transformation plasticity including morphological anisotropy is developed.•It is based on the theory of limit-analysis developed by Drucker and Hill.•It is backed vs. FFT simulations of RVEs with many growing nuclei of daughter-phase.