On strain partitioning and micro-damage behavior of dual-phase steels

This work presents a model used to study strain partitioning and micro-damage initiation of various dual-phase steel microstructures. The model is formulated via continuum micro-mechanics and is solved in a finite-element framework. A phenomenological failure criterion is employed, calibrated and used to identify micro-damage initiation during plastic deformation.What is shown is how the primary microstructural parameters responsible for microstructural stress/strain fluctuations, namely phase strength contrast and hard phase fraction, influence phase averaged strains and phase specific strain distributions. Results of a study on micro-damage initiation show the influence of these primary microstructural parameters on strain for micro-damage initiation, the associated macro stress, and strain hardening.It is concluded that with rising microstructural mechanical heterogeneity, strain for micro-damage initiation decreases and strain hardening increases. Macroscopic stress at micro-damage initiation is shown to be primarily governed by the hard phase fraction and secondarily by the phase strength contrast.