Computational modeling of dual-phase steels based on representative three-dimensional microstructures obtained from EBSD data

Abstract

The microstructure of dual-phase steels consisting of a ferrite matrix with embedded martensite inclusions is the main contributor to the mechanical properties such as high ultimate tensile strength, high work hardening rate, and good ductility. Due to the composite structure and the wide field of applications of this steel type, a wide interest exists in corresponding virtual computational experiments. For a reliable modeling, the microstructure should be included. For that reason, in this paper we follow a computational strategy based on the definition of a representative volume element (RVE). These RVEs will be constructed by a set of tomographic measurements and mechanical tests. In order to arrive at more efficient numerical schemes, we also construct statistically similar RVEs, which are characterized by a lower complexity compared with the real microstructure but which represent the overall material behavior accurately. In addition to the morphology of the microstructure, the austenite-martensite transformation during the steel production has a relevant influence on the mechanical properties and is considered in this contribution. This transformation induces a volume expansion of the martensite phase. A further effect is determined in nanoindentation test, where it turns out that the hardness in the ferrite phase increases exponentially when approaching the martensitic inclusion. To capture these gradient properties in the computational model, the volumetric expansion is applied to the martensite phase, and the arising equivalent plastic strain distribution in the ferrite phase serves as basis for a locally graded modification of the ferritic yield curve. Good accordance of the model considering the gradient yield behavior in the ferrite phase is observed in the numerical simulations with experimental data.Keywords Reconstruction of microstructure · Dual-phase steel · RVE · Microheterogeneous materials · EBSD-FIB · SSRVE · Volume expansion of martensite · Multiscale simulations

Materials knowledge system for nonlinear composites

“…to the classical composite theories with the major advances made in recent years in the field of computational mechanics [38]. Computational homogenization includes numerical techniques such as the micromechanical finite element models (e.g., [39][40][41][42][43][44][45]) and the FFT-based methods [46][47][48][49]. More recent developments have included the variational asymptotic method for unit cell homogenization [50].…”

Modeling of structures with polymorphic uncertainties at different length scales

“…Here, the example of DP steel is carried out based on a measurement from Brands et al with the size of 16 mm by 2 mm. The resulting distribution of the distance functional is shown in Figure a.…”

Simulation of Dual‐Phase Steel Using the Finite Cell Method and Voxel‐Based Microstructure Data

“…The corresponding integration meshes are shown in Fig. According to [1], the initial volumetric strain (IVS) approach is applied to capture a physical effect arising from the transformation of austenite to martensite during the production process. 1c and Fig.…”