Effect of martensite strength on the tensile strength of dual phase steels

Fe-2% Si-1.5% Mn steels with three levels of carbon content (0.10, 0.14 and 0.19wt%) were intercritically annealed followed by water quenching to obtain dual phase (martensite plus ferrite) structure. It is found that the ultimate tensile strength of dual phase steels increased with increasing the volume fraction as well as the tensile strength of martensite. The tensile strength of dual phase steel can be predicted using the law of mixtures although the predicted tensile strength is slightly higher than the experimental one. It is suggested that martensite never reaches its ultimate tensile strength when the necking of dual phase steels occurs.