Effect of rolling and epitaxial ferrite on the tensile properties of low alloy steel

A low alloy steel containing 0.09% C was thermomechanically processed at the intercritical annealing temperature of 790 C to produce dual-phase microstructure from 50% of austenite. After applying different rolling reductions at this temperature, the specimens were quenched in boiling water to promote the growth of epitaxial ferrite. Warm rolling at 790 C decreased the hardenability of austenite due to increased in interfacial area of austenite and ferrite. Tensile strength was improved by increasing the rolling reductions both in longitudinal and transverse directions without any significant loss in ductility attributed to the presence of epitaxial ferrite. Microvoid formation in the necked region and their percentage area fraction was measured. The correlation between the area fractions of microvoids formation with strain in the necked region ultimately defined the mode of failure.