Very strong low temperature bainite

Abstract

Bainite has been obtained by heat treatment at temperatures as low as 125°C in a high carbon, high silicon steel. This has had the effect of greatly refining the microstructure, which is found to have a strength in excess of 2.5 GPa together with an ability to flow plastically before fracture. Such properties have never before been achieved with bainite. In this paper metallographic details are reported of the very fine bainitic microstructure associated with the incredibly low transformation temperature, where during the time scale of the experiments, an iron atom cannot diffuse over a distance greater than ∼ 10^-17 m. Yet, the microstructure has a scale in the micrometre range, consistent only with a displacive mechanism of transformation.