Development of wear resistant medium carbon dual phase steels and their mechanical properties

Abstract

Dual phase (DP) steels containing four different amounts of martensite ranging from 42 to 72 vol.-% have been developed from 0.42 wt-% carbon normalised steel by intercritical heat treatment at a fixed temperature of 740°C but varying holding times followed by water quenching. Mechanical properties of dual phase steels with increasing volume fraction of martensite have been investigated highlighting the effect of martensite content. The macrohardness has been found to increase with increasing martensite content in dual phase steel. The yield and tensile strengths have been found to increase with increasing amount of martensite whereas the percentage elongation and the percentage area reduction have been found to decrease. This has been attributed to the presence of hard and brittle martensite phase, which increases the strength at the expense of ductility. The mode of fracture has been found to change from purely ductile to mixed (ductile + brittle) as the martensite volume fraction increases from 42 to 72% in dual phase steels. Friction and wear properties under dry sliding conditions have also been found to improve with increasing martensite volume fraction in dual phase steels. The applications of medium carbon DP steels in the field of mineral processing and mining have been discussed.