Relative effects of Mo and B on ferrite and bainite kinetics in strong steels

Well-designed cementite-free bainitic steels are important in contributing to unique combinations of strength, toughness and cost. We examine here the relative effects of molybdenum and boron on the kinetics of transformation of austenite particularly into allotriomorphic ferrite and bainite. There are some surprising results on the role of boron, which is found in some circumstances to accelerate the transformation to allotriomorphic ferrite. This, and other features of transformation behaviour are assessed in the context of phase transformation mechanisms.