Prediction of Temperatures of Austenite Equilibrium Transformations in Steels During Thermomechanical Processing

Prediction of Proper Temperatures for the Hot Stamping Process Based on the Kinetics Models

“…It is clear that the temperatures of the points in contact with the punch (points 1-5) are almost equal, and the same conditions also exist for the points in contact with the die (points [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. According to the slight temperature differences in each of these two regions, in order for reducing calculations, the thermal histories of the points P and D (1 and 26) were considered as the representatives of those of other points in contact with the punch and die, respectively, for the final calculations of the microstructure predictions.…”

“…The chemical potentials were calculated using the Wagner expansions of the activity coefficient ( Ref 28), and the required parameters were extracted from the Ref 11,15,[28][29][30] For determining DG Mechanical c , the following equation was used assuming the complete plastic deformation energy store in austenite (Ref 15):…”

“…Previous studies show that the stored plastic deformation energy in austenite has different effects on several austenite transformations. It raises the transformation rate of austenite to ferrite and pearlite (Ref 9,10,(15)(16)(17)(18)(19)(20) ) models are the most known. However, these models have limitations and problems ( Ref 10,12,19), which one of the most important ones can be the existence of empirical parameters in their equations requiring fitting equations to experimental data.…”