Designing low carbon, low temperature bainite

Abstract

The possibility of producing bainite at low temperatures by suppressing transformation using substitutional solutes has been investigated, as an alternative to using large carbon concentrations to achieve the same purpose. It is found that although transformation temperatures can indeed be suppressed in this way, the difference between the bainite and martensite start temperatures diminishes. This, combined with the relatively low carbon concentration of the steels studied, promotes the coarsening of the microstructure via a coalescence of fine bainite plates, which may have detrimental consequences on the properties although this remains to be demonstrated. The study also reveals the need for a better interpretation of the bainite start temperature to cover circumstances where the transformation times are unusually long.