HOT DEFORMATION BEHAVIOR OF A HIGH STRENGTH CONTAINER STEEL COMPOUNDED WITH Nb-B

Hot deformation behaviors of high strength container steel compounded with Nb-B have been systematically studied through high temperature compression tests on the Gleeble-1500 thermal-mechanical simulator. In the present deformation conditions, there are different relationships between the strain hardening exponent (n) and the true strain (epsilon) under different strain rates at the deformation temperature of 1423 K; n-epsilon curves have single peak and single valley at the strain rates of 0.1 s(-1) and 1 s(-1), while n-epsilon curves have double peaks and double valleys at the strain rates of 5 s(-1) and 15 s(-1). During the heat work-hardening process, dislocation strengthening, twin strengthening and precipitation strengthening are the major work-hardening mechanisms of the tested steel. According to Zener-Hollomon and Ludwik equation, the experimental data have been regressed by using nonlinear method, the apparent deformation activation energy (Q) and stress exponent (n) were obtained to be about (428.188 +/- 20.109) kJ/mol and 4.923 in the temperature range of 1123 K-1423 K, respectively. Finally, an expression of Z parameter, hot deformation equation and dynamic recrystallization model diagram of the tested steel are established.