Experimental
The composition of the steel used for the experiments is shown in Table 1, along with its ortho-equilibrium and para-equilibrium Ae3 temperatures. These values were calculated using the FactSage thermodynamic software, employing the FSStel Database® [13]. Materials were provided by Finkl Steel-Sorel, Canada. Cylindrical specimens were machined from the central region of the as-cast ingot with diameters and heights of 10 mm and 15 mm, respectively. Hot compression tests were performed using a Gleeble 3800® thermomechanical simulator following the procedures described in ASTM E209. The schematic diagram for double-hit compression tests is shown in Fig. 1. Two temperatures (1200 °C and 1150 °C), two strain rates (0.25 s-1 and 0.5 s-1), and one interpass time (5 s) were employed in the experiments.
Table 1: Composition of medium-carbon low-alloy steel.