BAINITE : OVERALL TRANSFORMATION KINETICS

Abstract
New experimental results on the overall transformation kinetics of the bainite reaction (in three different steels) are interpreted in terms of recent work on the transformation mechanism of bainite. The analysis is shown to be consistent with (a) a linear dependence of the activation energy for isothermal nucleation, on the transformation free energy change, (b) the sub-unit mechanism of bainitic transformation, (c) the variation of nucleation rate with the degree of transformation, (d) hard and soft impingement effectsand (e) alloying element effects. It is also suggested that the more conventional methods of analysing the overall transformation kinetics are inconsistent with the experimental results, and with the need to understand alloying element effects.