Effect of Silicon on the Hot Flow Behavior of Ultra-Low Carbon Austenite

The influence of silicon on the high-temperature deformation behavior of ultra-low carbon austenite was studied in the range of temperature and strain rate from 1,000 to 1,100°C and 0.001 to 0.1 s−1, respectively. The flow curves of the steels exhibit the classic softening due to dynamic recrystallization. The characteristic pairs of stress-strain values (zero, critical, peak, saturation, and steady state) were determined by the analysis of the work hardening curves. These values were analyzed by applying first the classical Sellars and McTegart approach. Once the apparent stress exponents and activation energies were determined as being in the vicinity of 5 and above 270 kJ/mol, respectively, a modified hyperbolic sine equation was used. The flow curves were characterized by work hardening, dynamic recovery, and recrystallization terms at any processing conditions, showing a direct relationship with the silicon content of the steels. Finally, all the flow curves of studied steels were discussed and modeled as a function of the processing parameters and silicon content.