Effect of Transformation Temperature on Microstructure andMechanical Properties of Bainite


Fully bainitic microstructure can be obtained by isothermal transformation attemperatures within the range of bainite transformation. Both transformation temperatureand time determine the phase fraction, the scale of the resultant microstructure and thecarbone content of the retained austenite, which in turn determine the mechanicalproperties.In this study, the thermomechanical simulator was used to obtained the fully bainiticmicrostructure for the high carbon alloy steel (0.78%C) at a different bainitetransformation temperatures (200 to 350°C) in order to study the effect of the isothermaltransformation temperature on the resultant mechanical properties.It has been concluded from the detailed analysis of the microstructure, the dilatometricdata and the mechanical properties (hardness and tensile properties) that finer bainite andless retained austenite phase fraction can be obtained by transformation at lowertemperatures, and that leads to exceptional mechanical properties (Hardness ≈ 660 HV,and Tensile strength ≈ 2 Gpa).