Direct Ageing of Alloy GH169

For the purpose on application of direct aging (DA) GH169 in production a comparison of direct ageing treatment and standard heat treatment following hot deformation is conducted. Direct ageing treatment can get higher tensile strengthes and raise smooth specimen stress rupture lives remarkably. However, both notched specimen stress rupture aud cyclic stress rupture lives decrease because of the low ductility. The creep damage during creep and fatigue interaction condition is also enhanced. The reason may be smaller amount δ precipitate distribution at grain boundaries and the grain boundary cohesive force can not perfectly match grain strength, then the strengthening and ductility improvemeat can not reach simultaneously. Grain refinement and dislocation configuration control at the hot deformation process are most important factors to control the suitable amount and distribution of δ-phase.