Abstract

During thermomechanically controlled processing (TMCP) of carbon steels, controlled rolling in norecrystallization regime followed by directing quenching results in excellent mechanical properties, besides enabling cost-saving in respect of energy costs normally incurred during reheating and quenching procedure. The effects of three different combinations of Cr with 0.06 wt.% of Nb on the microstructures and mechanical properties of thermomechanically rolled and direct-quenched low-carbon (0.035 wt.%) microalloyed steel plates have been investigated to obtain balanced mechanical properties. Laboratory-scale ingots were cast, hot rolled and direct quenched into 12 mm thick plates as per an experimental plan. Tensile properties, impact toughness, hardness and hardenability were studied. In addition, coarse grained heat affected zone (CGHAZ) simulations were performed in a Gleeble simulator to evaluate the weldability of the investigated steels using cooling time from 800 °C to 500 °C (t_8/5) of 5 s and 15 s.