摘要
系统探讨了不同时效温度(600℃与650℃)及时效时间(3000h、5000h、10000h)对GH4706合金微观组织演变及其室温拉伸与高温持久性能的影响。结果表明:随时效温度升高与时间延长,晶粒尺寸显著增大,其中650℃×10000h时效后晶粒尺寸达125μm;经高温长时间时效后,晶界η相由弥散颗粒加速演变为连续网状,同时晶内碳化物(主要为MC和M_(23)C_6型)持续粗化,在650℃×10000h条件下最为严重;经室温拉伸后的样品,其断后伸长率对时效温度更敏感,而抗拉强度对时效时间更敏感;经高温持久试验后的样品,其性能则严重受制于晶界处析出物的类型,M_(23)C_6型碳化物与η相共同作用促进裂纹萌生与扩展,导致650℃×10000h试样持久寿命急剧下降。综上所述,G H4706合金在高温长期服役中的性能退化核心机制是晶界η相连续网格化与碳化物粗化共同引发的晶界脆化,影响其力学性能。
This study systematically investigates the effects of different aging temperatures(600C and 650C)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 650C×10000h.Following high-temperature aging,the grain boundary n 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 650C×100o0h 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 n phase act synergistically to promote crack initiation and propagation,leading to a drastic reduction in the stress rupture life of the 650C×10000h sample.In conclusion,the core mechanism behind the performance degradation of GH4706 alloy during hightemperature long-term service is grain boundary embrittlement,induced by the combined effects of the continuous network of grain boundary n phase and the coarsening of carbides,which collectively deteriorate its mechanical properties.
作者
袁琴
徐松哲
王冲
段然
侯雨阳
陈超越
玄伟东
任忠鸣
YUAN Qin;XU Songzhe;WANG Chong;DUAN Ran;HOU Yuyang;CHEN Chaoyue;XUAN Weidong;REN Zhongming(School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China;State Key Laboratory of Advanced Special Steels,Shanghai 200444,China;Key Laboratory of Materials Anisotropy and Texture,Ministry of Education,Northeastern University,Shenyang 110819,Liaoning,China;Gaona Aero Material Co.,Ltd.,Beijing 100081,China)
基金
国家重点研发计划项目(2022YFB3705105)。
关键词
GH4706合金
时效处理
组织演变
析出相
力学性能
GH4706 alloy
aging treatment
microstructural evolution
precipitates phase
mechanical properties
