DP-GH4169合金在Delta工艺中的热变形行为及机制  

Hot Deformation Behavior and Mechanism of DP-GH4169 Alloy during Delta Process

作　　者：张海燕[1] 程明[2] 胡如夫[1] 张士宏[2] 赵忠[1] Zhang Haiyan;Cheng Ming;Hu Rufu;Zhang Shihong;Zhao Zhong(School of Mechanical and Automotive Engineering,Ningbo University of Technology,Ningbo 315336,China;Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China)

机构地区：[1]宁波工程学院机械与汽车工程学院,浙江宁波315336 [2]中国科学院金属研究所,辽宁沈阳110016

出　　处：《稀有金属》2024年第5期651-659,共9页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(51505240);浙江省零件轧制成形技术研究重点实验室项目(PR20002)资助。

摘　　要：相是镍基变形高温合金GH4169合金中主要强化相γ″的稳定相,以δ时效处理后的GH4169(Delta processed GH4169,DP-GH4169)合金为研究对象,通过等温恒应变速率压缩实验,在温度为954~996℃和应变速率为0.001~0.1 s^(-1)的范围内研究了该合金在Delta工艺中的热变形行为,获得了合金的热变形激活能和应变速率敏感因子,建立了功率耗散图。通过光学显微镜(OM)、透射电镜(TEM)和电子背散射衍射(EBSD)分析了该合金在Delta工艺热变形时的变形机制和微观组织演变机制。结果表明,DP-GH4169合金在Delta工艺热变形中的微观组织演变机制为动态再结晶(DRX)和片层状δ相的球化;变形激活能为332.276 kJ·mol^(-1);片层状δ相的球化行为与晶界滑移机制的相互作用,导致合金在应变速率范围为0.001~0.1 s^(-1)变形时应变速率敏感因子的变化规律不同;基于功率耗散图,DP-GH4169合金在高于980℃变形时,高应变速率更有利于获得细晶;在温度为957~971℃和应变速率为0.001~0.004 s^(-1)的范围内变形时,DP-GH4169合金发生了超塑性变形。Ni-based Superalloy GH4169 is a precipitation strengthened alloy.The metastable body-centered tetragonal coherent precipitateγ″(Ni3Nb)phase and the face-centered cubic coherent precipitateγ΄(Ni3Al)phase are strengthening phases,and theγ″phase is the major strengthening phase.The equilibrium phase corresponding toγ″phase is the orthorhombic incoherentδ(Ni3Nb)phase.GH4169 alloy is an important material used for aviation and aerospace engines.The mechanical properties of GH4169 alloy are sensitive to microstructure.In order to improve the safety and reliability of engines,it is crucial to obtain the forging with a uniform and fine microstructure.Generally,the forgings with large size and complex shape,such as turbine disks and engine shafts,are manufactured by multi-stage hot working processes.In addition,the microstructure of the alloy is sensitive to the hot deformation parameters.Therefore,the defects of coarse grain and duplex grain always appear in the forgings.Based on the MinigrainTM processing and the strong pinning effect ofδphase on the grain boundaries in GH4169 alloy,Delta process(DP)has been applied to the forging of GH4169 alloy,which uses an intentionalδphase precipitation cycle and subsequent thermomechanical processing to obtain the forging with uniform fine grains.The processing maps have been developed on the basis of dynamic material model(DMM).In this model the workpiece under hot working is considered to be a dissipater of power.The processing mapis composed of the power dissipation map and the instability map.The variation of the efficiency of power dissipation(η)with deformation temperature and strain rate constitutes the power dissipation maps.The various domains in the map are correlated with specific microstructural evolution processes.Therefore,the processing maps have been widely applied to understand the workability of materials and optimize the hot working process.The effect ofδphase on the deformation behavior and the microstructure evolution of GH4169 alloy during the

关 键 词：变形行为 GH4169合金 Delta工艺(DP) 功率耗散图 Δ相 

分 类 号：TG146.15[一般工业技术—材料科学与工程]