Direct measurement of carbon enrichment during austenite to ferrite transformation in hypoeutectoid Fe-2Mn-C alloys

Carbon enrichment in untransformed austenite at the end of Mn partitionless growth of ferrite for Fe-2Mn-(0.05, 0.14)C (mass%) alloys isothermally transformed in the temperature range 873-998 K was measured using field-emission electron probe microanalysis to reveal its dependence on the transformation temperature, nominal carbon content and prior austenite grain size. The PLE/NPLE model gives much better predictions than the PE model for carbon enrichment in untransformed austenite at the end of partitionless growth. Carbon enrichment could be increased by reducing the prior austenite grain size. Furthermore, carbon enrichment shifted from the PLE/NPLE transition line to the T0 line on lowering the transformation temperature. This shift is probably attributed to the solute drag effect and/or to the finite interface mobility, both of which vary with the transformation temperature.