Characterization of Dual Matrix Structured Ductile Iron

Abstract

The dual matrix structured ductile iron consists of a soft phase(ferrite)and a hard phase(martensite).The combination of soft and hard phase increases the toughness and strength significantly and meets the requirement of automotive industries for their application in suspension parts.This investigation relates the variation of mechanical properties of dual matrix structured ductile iron with different ferrite and martensite volume fraction as the microstructure and amount of distribution of these phases control the mechanical properties.The DMS ductile iron was obtained by heating the as cast ductile iron to intercritical austenizing temperature of 800°C then holding for 2 mins and followed by quenching in mineral oil.The ferrite and martensite volume fraction was calculated by image analysing software.The effect of ferrite and martensite volume fraction on tensile strength,yield strength and percentage elongation was studied.In this investigation it was found that the Ultimate tensile strength increases and ductility decreases with the increase in martensite volume fraction and decrease in ferrite volume fraction.The dual matrix structured ductile iron with higher volume fraction of martensite results in higher tensile strength and hardness and reduction in ductility.And subsequently the DMS ductile iron with higher ferrite volume fraction results increase of ductility and decrease of hardness and tensile strength.The ultimate tensile stress of DMS ductile iron is much higher than ferritic grades and ductility is somewhat lower than ferritic grade of ductile iron.