Effect of Niobium (Nb) and molybdenum (Mo) additions in the microstructure tensile property
Prior work shows that a significant synergetic effect on hardenability can be reached combining Boron with microalloying elements (adding Nb, Mo or Nb-Mo). To explore more this effect of microalloying elements and thermomechanical rolling schedule, laboratory thermomechanical simulations reproducing plate mill conditions were performed using ultra high strength steels micro-alloyed with Nb, Mo, and Nb-Mo.
Insights from Plane Compression Tests and Microstructural Evaluation
Plane compression tests, including preconditioning, deformation passes, and quenching, were conducted, followed by rapid cooling and tempering. This study extensively evaluated the interplay between martensitic microstructure, tempering treatment, microalloying elements, and resulting tensile properties. Notably, the highest tensile properties were achieved by combining Nb and Mo.. Yield strength reduction after tempering also measured significantly lower, for NbMo micro-alloyed steel.