Characterization of hot deformation behavior of Ni-base superalloy Rene'41 using processing map

The hot deformation behavior of Ni-base superalloy Rene'41 has been investigated by isothermal compression in deformation temperature range from 850 to 1050 degrees C with strain rates of 0.1-50 s(-1) on Gleeble-3500 thermal simulation machine. The constitutive equation of the alloy is established, which describes the flow stress as a function of strain rate and deformation temperature. Based on dynamic material model and Prasad's instability criterion, the processing maps for the alloy are constructed at strains of 0.3 and 0.5. The processing map at the strain of 0.5 exhibits a single stable domain of 910-1050 degrees C at 0.1-1 s(-1) with a peak efficiency of about 45% occurring at 0.1 s(-1) and 960 degrees C. The dynamic recrystallization of the alloy can be easily observed at 1000 degrees C and 0.1 s(-1). With increasing deformation temperature and/or decreasing strain rate, the volume fraction of dynamic recrystallization increases. At strains of 0.3 and 0.5, the flow instability domain mainly located at higher strain rate (> 1.5 s(-1)). On the basis of processing map and microstructure evolution, the optimum processing conditions at the strain of 0.5 are in deformation temperature range between 950 and 1050 degrees C and strain rate range of around 0.1-1 s(-1). (C) 2013 Elsevier B.V. All rights reserved.