Figure 6
The line graph plots “True Stress [Megapascals]” on the y-axis, ranging from 0 to 1200 with an interval of 200, versus “True plastic strain [Unitless]” on the x-axis, ranging from 0 to 0.14 with an interval of 0.02. Six curves represent the behavior of D P 780 steel at different strain rates: quasistatic (Q S), 1 1 over s, 100 1 over s, 300 1 over s, 800 1 over s, and 1000 1 over s, shown as a solid black line, a dashed black line, a dotted black line, a dashed-dotted black line, a solid red line, and a dashed red line, respectively. The legend in the lower right matches each curve to its strain rate, demonstrating that D P 780 shows increased flow stress as loading rate increases. All curves increase steeply at first, then gradually level out with higher strain—stress values are higher at greater strain rates, indicating strong strain-rate sensitivity. On the upper side, the dashed red line starts from (0, 740), passes through (0.07, 1060), and ends at (0.14, 1150). On the lower side, the solid black line starts from (0, 530), passes through (0.07, 880), and ends at (0.14, 960). The other four line curves follow the same trend between these two lines. Note: All the numerical data values are approximated.True plastic strain vs true stress [MPa] for DP780 alloy steel at different strain rates. Source(s): Authors’ own creation, adapted from Sun et al.‘s (2019) study