Stress Relaxation Behavior and Creep Constitutive Equation of GH4169 Superalloy at High Temperature

Stress relaxation tests were carried out at various high temperatures(550,650 ℃ and 750 ℃)on GH4169 superalloy used for turbine disk,and the creep constitutive equations were built according to stress relaxation curves.The results show that the stress relaxation curves of GH4169 superalloy presented the same characteristics at different temperature,the stress relaxation process could be divided into the stage of fast relaxation and the stage of stabilization.Second order exponential decay function could be well used to describe the stress relaxation process of GH4169 superalloy.Throughout the entire stress relaxation process,the stress and creep strain rate curves could be divided into three stages,low stress stage,transition stage and high stress stage.The relationship of stress and creep strain rate in the low stress stage and the high stress stage both presented linear correlation.By fitting the stress and creep strain rate curves using software Origin 8.0,the material constants in creep constitutive equations of GH4169 superalloy were obtained.