The 3D representative volume element modelling concerning different microstructural features and renowned work hardeningmodels was developed in this study. Simulation results of stress–strain relationship based on the Kocks–Mecking modelexhibit satisfactory accordance with the experimental results compared to the Swift–Voce law and J2elastoplastic-basedtheory. The volume fraction of martensite has a great influence on the mechanical properties of the DP1180 steel. The resultsindicate that the plastic stress is mainly condensed in martensites and phase boundaries, while the plastic strain localisation ispredominantly detected in the ferrite grains and/or between two narrow martensites. To capture the stress–strain partitioningbehaviour and deformation particularities in DP1180, a further analysis based on evolving microstructure has been carriedout on various strain levels after tensile loading. It offers insights into the role of each constituent phase on the mechanicalproperties as well as the dominant shear failure modes of the DP1180.