Damage mechanism and modeling of void nucleation process in a ferrite–martensite dual phase steel

•Damage mechanism in a modern high strength dual phase steel was studied.•Interface decohesion of ferrite–martensite particles was the main cause of void nucleation.•Fracture occurred primarily by accelerated void nucleation in the final steps of tensile deformation.•Kinetics of voids evolution in specimens with lower triaxiality is faster than that in higher triaxiality conditions.•An empirical model for damage initiation in dual phase steels was proposed.

Damage initiation and growth behavior in high strength dual phase sheet steel, i.e. DP780, was investigated using smooth and notched tensile specimens. By SEM microstructural analyses of pulled and sectioned tensile specimens, void initiation and growth behavior were quantified. Finally, a simple model was proposed to predict the void nucleation kinetics for both kinds of specimens. The predicted values were in good agreement with the experimental data using the model.