A COMPARATIVE-STUDY OF OBSERVED AND PREDICTED AUSTENITE MICROSTRUCTURES DURING HOT-ROLLING OF A MEDIUM-CARBON STEEL

Two-step deformation sequences, applied by laboratory rolling to a med ium carbon steel, were used to assess the applicability of the most im portant models of microstructural evolution to describe the actual beh avior of the austenite in this material. The model developed by the IR SID group gave the best overall agreement with the metallographic obse rvations, mainly due to a better prediction of the rates of grain grow th in the temperature range of 1173 to 1473 K, as compared to the mode ls proposed by the researchers at Sheffield University and Nippon Stee l Corp., which predictions resulted grossly inaccurate at the higher t emperatures. Nevertheless, all three models contain the essential feat ures to lead to reasonable values of the austenite grain size, especia lly as the number of deformation steps increases concurrently with a p rogressive decrease in the temperatures of deformation.