Measurement of phase transformation temperatures under near-real conditions using a thermomechanical simulator

Phase transformations are normally studied under standard conditions using dilatometers and very small volumes of material. These conditions are given by historical definitions and do not fully correspond to real-world industrial processes any more. Transformation diagrams are a typical example here. They are constructed on the basis of dilatometric data measured at various cooling rates. Specimens are ordinarily cooled from temperatures to which they were brought under fixed conditions. However, real-world processes deviate from such agreed-upon conditions. The deviations often preclude accurate analysis of relevant phenomena which take place in the process. This was the motivation for exploring the possibilities of measuring phase transformation behaviour during physical simulation, while incorporating plastic deformation, which can alter the behaviour profoundly. This paper describes experiments performed on specimens of 22MnB5 steel. Metallographic observation using optical and scanning electron microscopy and HV10 hardness testing were employed. Results of the measurement were checked against metallographic findings which confirmed the accuracy and the information value of the methodology