This research presents an experimental characterization of ductile damage evolution in dual-phase steel containing 0.066 wt.% C, 0.0022 wt.% N, 1.219 wt.% Mn, 0.988 wt.% Si, 0.007 wt.% S, and 0.011 wt.% P. The samples were subjected to intercritical annealed at different temperatures from 800 to 850 °C and brine quenched to produce dual-phase steel microstructure with different martensite volume fractions. 

A set of loading-unloading uniaxial tensile tests was carried out to characterize the material damage, based on the measurements of the deterioration exhibited by Young’s modulus due to increasing levels of plastic deformation. Scanning electron microscopy (SEM) was used to observe the microstructure of the deformed samples. The martensite volume fraction (Vm) has a dominant role in the damage mechanisms. It was observed that by increasing the Vm, the material ductility is reduced while its ultimate tensile strength increases. Furthermore, the cyclically applied quasi-static strain causes a more rapid reduction in ductility than a typical uniaxial tensile test.