Bainitic-Martensitic steels - influence of transformation sequence and external loads on the phase transformation kinetics and the mechanical properties in low alloy steel

Abstract

The influence of phase transformation sequence and of loads superimposed during phase transformation on bainitic-martensitic steels was studied. Thorough sets of experiments shed light on the evolution of transformation plasticity (TP) strains, the phase transformation kinetics and the resulting mechanical properties. In particular, the superimposed loads increased the martensite start temperatures, accelerated the bainitic phase transformations and yielded the evolution of TP strains. Furthermore, when bainitic-martensitic microstructure was obtained by first transforming part of the austenite to bainite and the rest to martensite, the total transformation time was shortened; however the monotonic mechanical properties were inferior as compared to a microstructure were the martensite was formed prior to the bainite.