Evaluation of mechanical properties of ferrite-martensite DP steels produced through intermediate quenching technique

The objective of the present work is to investigate the mechanical properties of the dual phase (DP) steels produced by the intermediate quenching (IQ) technique. To produce the ferrite-martensite microstructure in the dual phase (DP) steel, low carbon micro alloyed steel is intercritically heat treated followed by short intercritical annealing and intermediate quenching using various intercritical temperatures. By varying the intercritical temperature (740, 760, 780, 800, 820 °C) different volume fraction of the ferrite and martensite phases of DP steel samples are produced. These series of dual phase (DP) steel samples were further analyzed through scanning electron and optical microscopy. The experimental investigations have been carried out to find the mechanical properties as per the ASTM testing standards. From the outcomes it is observed that DP780 steel have excellent tensile strength, better hardness and toughness which may be due to the fine distribution and equal volume fraction of ferrite and martensite phases. The enhancement in the mechanical properties of dual phase steel was the effect of intermediate quenching technique. Equal volume fraction of ferrite and martensite phases obtained, at temperature of 780 °C, converted low carbon micro alloyed steel into dual phase steel and also improves its mechanical properties.