Effect of Martensite Morphology on the Tensile Deformation Behavior of a DP590 Steel

Abstract

The automotive industry aims at the production of vehicles with low weight, fulfilling high requirements concerning safety improvements and reduced fuel consumption. Reduction of vehicle weight is believed to be the most promising factor responsible for significant improvement in fuel economy in the future. Dual phase (DP) steels of AHSS category are considered to be the most promising in achieving high strength with low weight. These steels derive their excellent combination of mechanical properties by second phase martensite and/or bainite in a ferrite matrix. Research conducted so far in dual phase steels provides the information about the effect of phase fraction of martensite on tensile properties of dual phase steels but lags to provide the effect of the morphology and distribution of the martensite islands on the tensile deformation behavior in dual phase steels. Thus, the present work is an attempt to look into effect of the morphology and distribution of the martensite islands on the tensile deformation behavior of dual phase steels. Additionally, an attempt is made to refine the martensite phase fraction and improve the mechanical properties without compromising on ductility. Martensite of fine size and that too mainly embedded within the ferrite grains has been found effective to retain high ductility at high ultimate tensile strength.