Effect of pre-deformation on the age hardening of a niobium-microalloyed steel

A niobium-microalloyed steel is aged at 640 °C after being solution-treated at 1200 °C. Nb(C,N) nanoparticle precipitation is markedly facilitated by a pre-deformation of 15% prior to ageing, leading to a considerable increase in the strength of the steel with no large decrease in ductility. The yield strength of the pre-deformed steel may reach about 710 MPa with an elongation of about 20% after peak aged.