TENSILE CREEP DEFORMATION AND DAMAGE BEHAVIOR IN A NICKEL-BASE SUPERALLOY AT 900℃
来源期刊：Acta Metallurgica Sinica2004年第4期
论文作者：H.C.Yu H.C.Yang S.S.Xie
Key words：creep deformation and damage; dislocation; microstructure; superalloy;
Abstract: The tensile creep deformation and damage evolution in a Ni-base superalloy at 900℃/170MPa were investigated. At the first creep stage, abnormal creep occured due to the resolution of fine particles, and the deformation initiated from grain boundary areas. It is evident that nearly all of the dislocations were in γ matrix channels in form of dislocation pairs and the dislocations were impeded at γ/γ′ interfaces, thus the dislocation networks developed deformation. At the steady creep stage, impeded dislocations at γ /γ′ interfaces climbed over γ′ phases by diffusion-dominant mechanism.At the last creep stage, voids were formed around carbides at grain boundary which leaded to accumulated damage and caused creep rate accelerated. With the dislocation networks being broken, the voids connected and grew into micro-cracks gradually.Finally the cracks propagated along grain boundary area and resulted in failure.
H.C.Yu1，H.C.Yang2，S.S.Xie3
(1.Beijing Institute of Aeronautical Materials, Beijing 100095, China;
2.College of Materials and Metallurgy, Northeastern University, Shenyang 110004, China;
3.R & D Center, Baosteel Co. Ltd., Shanghai 201900, China)
Abstract:The tensile creep deformation and damage evolution in a Ni-base superalloy at 900℃/170MPa were investigated. At the first creep stage, abnormal creep occured due to the resolution of fine particles, and the deformation initiated from grain boundary areas. It is evident that nearly all of the dislocations were in γ matrix channels in form of dislocation pairs and the dislocations were impeded at γ/γ′ interfaces, thus the dislocation networks developed deformation. At the steady creep stage, impeded dislocations at γ /γ′ interfaces climbed over γ′ phases by diffusion-dominant mechanism.At the last creep stage, voids were formed around carbides at grain boundary which leaded to accumulated damage and caused creep rate accelerated. With the dislocation networks being broken, the voids connected and grew into micro-cracks gradually.Finally the cracks propagated along grain boundary area and resulted in failure.
Key words:creep deformation and damage; dislocation; microstructure; superalloy;
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