On the hot deformation behavior of AISI 420 stainless steel based on constitutive analysis and CSL model

We describe here the hot deformation behavior of AISI 420 stainless steel using hot compression tests in the temperature range of 950-150 degrees C and strain rate of 0.01-10 s(-1). By considering the relative material constants as a function of strain with sixth polynomial fitting, the effect of strain was studied using an Arrhenius type constitutive equation. The deformation activation energy was estimated to be in the range of 362-435 kJ/mol. The constitutive equations developed were consistent with the experimental data using standard statistical parameters. The Z-parameter map at the strain of 0.6 was plotted and it can be concluded that the occurrence of DRX is associated with the condition that ln Z is less than 32 s(-1). The lower Z-parameter indicates the larger extent of dynamic softening, especially the process of DRX. It is worth noting that the most dominant CSL boundary is the Sigma 3 twin boundary, the fraction of which remains constant after the process of DRX. However, the fraction of Sigma 11 boundary, Sigma 33c boundary, and Sigma 41c boundary is almost at the same level, which is approximate a quarter of the Sigma 3 fraction and decreases slightly after DRX. (C) 2013 Elsevier B.V. All rights reserved.