Correlation between strain-rate sensitivity and dynamic softening behavior during hot processing

This paper has quantitatively investigated strain-rate sensitivity (SRS) coefficients m for hot processing with different dynamic softening (DS) behavior. Isothermal compression experiment of TC18 titanium alloy has been conducted for verification and relevant sensitivity coefficients have been obtained from Arrhenius constitutive function. Kocks-Mecking model has been employed to estimate SRS coefficients for dynamic recovery (DRV) process and SRS values maintain stable at 0.2. SRS coefficients for dynamic recrystallization (DRX) process have been calculated from JMAK kinetic model and the values have been obtained over 0.3 with obvious sensitivity to parameter variation. Dependence of strain-rate sensitivity on dynamic softening behavior has been demonstrated in comparison with dislocation evolution map. Microstructure evolution incorporating different SRS values has been analyzed under deformation parameter variation. Power dissipation efficiency distribution map for hot deformation of TC18 alloy has been constructed from SRS values in quantized characterization on DS behavior. (C) 2015 Elsevier B.V. All rights reserved.