Damage Behavior in Modern automotive High Strength Dual Phase Steels During Uniaxial Tensile Deformation

In the present research, damage mechanisms during room temperature uniaxial tensile testing of two differentmodern high strength dual phase steels,dp780 and dp980, were studied. detailed microstructural characterizationof the strained and sectioned samples was performed by scanning electron microscopy (sem). the results revealedthat interface decohesion, especially at the triple junctions of ferrite-ferrite-martensite, was the most probablemechanism for void nucleation. also, it was found that ductile fracture in these steels was nucleation controlledsuch that just before ductile fracture incidence, a high density of voids would nucleate or a sudden acceleratedvoid nucleation could happen. microscopic observations as well as statistical analysis confirmed this phenomenon.moreover, damage analysis suggested that the void nucleation rate was higher in dp980 than dp780 steel. itseemed to be highly influenced by the morphology and distribution of martensite particles within the ferrite matrix