Analysis of banded microstructures in multiphase steels assisted by transformation-induced plasticity

• Published in: Computational materials science 2014-03, Vol.84, p.339-349
• Main Authors: Yadegari, S., Turteltaub, S., Suiker, A.S.J., Kok, P.J.J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Banded microstructures; Computation; Dispersion; Elasticity. Plasticity; Exact sciences and technology; Ferritic stainless steels; Grains; Homogenizing; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microstructure; Multilevel non-convex Voronoi tessellation; Multiphase; Non-redundant periodic boundary conditions; Numerical homogenization; Steels; TRIP steel
• ISSN: 0927-0256; 1879-0801
• DOI: 10.1016/j.commatsci.2013.12.002

•Randomly-dispersed grains of austenite increase the shear strength of a TRIP steel.•Clustered grains of austenite do not necessarily increase the shear strength.•Clustering of austenite facilitates plastic localization in the ferritic matrix. The influence of the spatial distribution of the austenitic phase on the effective mechanical properties of a multiphase steel assisted by transformation-induced plasticity is analyzed using a numerical homogenization scheme. Representative three-dimensional volume elements with distinct microstructures are created applying a newly-developed algorithm based on the generation of a multilevel Voronoi tessellation; this approach allows for straightforwardly incorporating grains with complex, non-convex shapes in the microstructure. The effective macroscopic response of the samples is computed under the formulation of a set of non-redundant, periodic boundary conditions, which warrants a consistent transition between the microscopic and macroscopic scales. A sample in which austenitic grains are clustered within a ferritic matrix by means of a band-like region is compared to a sample with austenitic grains being randomly dispersed within the ferritic matrix. It is found that the banded microstructure may be detrimental in comparison to the dispersed microstructure, since it allows substantial plastic localization to occur in the ferritic matrix, which in turn diminishes the strengthening effect provided by the austenitic phase.