GH4706合金在不同时效下的析出相演化及其对力学性能的影响OA

This study systematically investigates the effects of different aging temperatures(600℃ and 650℃)and aging times(3000h、5000h、10000h)on the microstructural evolution,room-temperature tensile properties,and high-temperature stress rupture properties of GH4706 alloy.The results indicate that the microstructure coarsens significantly with increasing aging temperature and time,with the grain size reaching 125μm after aging at 650℃ × 10000h.Following high-temperature aging,the grain boundary η phase evolves rapidly from dispersed particles into a continuous network,while the intragranular carbides(primarily MC and M23C6 types)undergo continuous coarsening.This process is most severe under the 650℃ × 10000h condition.The study reveals that during room-temperature tensile testing,the elongation after fracture is more sensitive to temperature,whereas the ultimate tensile strength is more sensitive to time.The high-temperature stress rupture performance is critically dependent on the precipitates at the grain boundaries;M23C6 carbides and the η phase act synergistically to promote crack initiation and propagation,leading to a drastic reduction in the stress rupture life of the 650℃ × 10000h sample.In conclusion,the core mechanism behind the performance degradation of GH4706 alloy during high-temperature long-term service is grain boundary embrittlement,induced by the combined effects of the continuous network of grain boundary η phase and the coarsening of carbides,which collectively deteriorate its mechanical properties.