Hot deformation behavior of GH4169 superalloy associated with stick 8 phase dissolution during isothermal compression process

Isothermal compression tests of the post-delta treated GH4169 superalloy has been taken carried out on a Gleebe 1500D simulator at the strain rates of 0.001-1.0 s(-1) and temperatures of 940-1060 degrees C. A constitutive equation represented as a function of temperature, strain rate and true strain was developed, and the hot deformation apparent activation energy is calculated about 523 kJ/mol. A processing map (epsilon = 0.69) was constructed on the basis of experimental data for evaluation of efficiency of power dissipation (eta), identification of instability regions. Hot deformation process can be carried out stability and safely in two domains of (T-d: 1020-1060 degrees C, (epsilon) over dot : 0.01-1.0 s(-1)) and (T-d: 940-980 degrees C, (epsilon) over dot : 0.001-0.01 s(-1)). However, the processing map predicts one instability region occurred around (T: 940 degrees C, (epsilon) over dot :1.0 s(-1)) with stick delta phase content of about 14%. The delta phase takes great effect on DRX and flow behavior during hot deformation process. An equation that describes delta phase content as a function of strain rate and absolute temperature may be written as V(delta) = -(3.92 . log((epsilon)) over dot/T) + (890.9/T)+0.02033.log((epsilon)) over dot - 0.58469 used the least square method for GH4169 superalloy processed under the conditions of (T-d: 940-1020 degrees C, : 1.0-0.01 s(-1)). Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.