Effect of the δ phase on the deformation behavior in isothermal compression of superalloy GH4169

The effect of the delta phase on the deformation behavior, including flow stress-strain curve, strain rate sensitivity exponent, strain hardening exponent and kinetic analysis, was investigated by isothermal compression of superalloy GH4169 with two kinds of solution treatment. The experimental results show that the existence of delta phase results in the decreasing of flow stress, and makes the flow stress reach a peak value at small strain. The strain rate sensitivity exponent (m) increases with the increasing of deformation temperature. The existence of delta phase leads to the increasing of strain rate sensitivity exponent (m) at a certain deformation temperature and strain. Moreover, the strain hardening exponent (n) has a close relationship with the deformation temperature, strain rate and strain, especially the strain affects n more significantly. The existence of delta phase results in the decreasing of n values, and makes the n values reach a negative value at small strain. It was observed that the changes in strain rate sensitivity exponent and strain hardening exponent were closely related to the microstructural evolution in the deformation process. Based on the kinetic analysis of superalloy GH4169 with two kinds of solution treatment, the apparent activation energy of superalloy GH4169 containing delta phase was calculated to be 476.136 kJ mol(-1), which was slightly higher than that of superalloy GH4169 (455.434 kJ mol(-1)) without 3 phase. And the peak flow stress in the isothermal compression of superalloy GH4169 was observed to increase with the increasing of parameter Z. (C) 2011 Elsevier B.V. All rights reserved.