再热恢复处理对蠕变损伤定向凝固高温合金γ′相的影响
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摘要
以定向凝固GTD111合金为研究对象,采用蠕变中断实验获得蠕变损伤合金,之后对损伤合金进行简单再热恢复处理,研究了恢复参数对合金组织的影响以及γ′相的恢复演化过程。结果表明,1180～1220℃下固溶处理可有效溶解粗化形变γ′相并析出二次γ′相,且二次γ′相尺寸随固溶温度和冷却速率的增加而减小,但当固溶温度增至1240℃,合金发生初熔;高温时效是二次γ′相长大和三次γ′相析出的过程,且二次γ′相尺寸和立方度随时效温度和保温时间的增加而增大;低温时效中三次γ′相继续析出和长大。GTD111损伤合金的合适恢复参数为:1220℃、2 h、AC+1121℃、2 h、AC+843℃、24 h、AC。由于恢复态合金具有更大体积分数的双尺寸形态γ′相,其在750℃、843 MPa下的持久寿命达到65 h,是原始合金持久寿命的1.3倍。
As the core hot section components in gas turbine systems, the turbine blades are inevitably subjected to various microstructure creep damages after long time service, which seriously affect their service life. The hot isostatic pressing(HIP)-combined rejuvenation heat treatment process has been developed as a critical step in refurbishment of degraded blades with equiaxed structure, and there is a common view that HIP process has positive impact on healing creep cavities, however, the turbine blades in current gas turbine systems are widely made of directionally solidified superalloys with excellent resistance of creep voids due to the minimal number of oriented grain boundaries, which indicates that it is likely to use simple re-heat rejuvenation treatment consisting of solution and ageing treatments as a cheaper refurbishment method in recovering microctructures and properties of directionlly solidified superalloys. In this work, the interrupted creep test was conducted on directionlly solidified GTD111 superalloy to simulate the service damage of turbine blades. The effect of re-heat rejuvenation treatment on γ ′ precipitates microstructure of creep degraded GTD111 superalloy and the evolution process of γ ′ precipitates under different stages of re-heat rejuvenation treatment were investigated. The results show that solid solution treatment at the temperature range of 1180～1220 ℃ can effectively dissolve the coarsened and rafted primary γ ′ precipitates and promote uniform precipitation of fine size secondary γ ′ precipitates in the damaged alloy, meanwhile the size of secondary γ ′ precipitates decreases with the increase of solution temperature and cooling rate. However, when the solid solution temperature increases to 1240 ℃,incipient melting in the interdendritic region ocurrs. High temperature ageing results in continued growth of the secondary γ ′ precipitates and precipitation of tertiary γ ′ precipitates. The size and cubic degree of the secondary γ ′ precipitates increase with the increase of ageing temperature and soaking time. The tertiary γ ′ precipitates continue to precipitate and grow during low temperature ageing process. The suitable re-heat rejuvenation parameters are 1220 ℃, 2 h, AC+1121 ℃, 2 h, AC+843 ℃, 24 h, AC. The rupture life of rejuvenated alloy under the condition of 750 ℃ and 843 MPa is up to 65 h, which is about 1.3 times of that of virgin alloy, due to its more volume fraction of duplex size γ ′ precipitates after re-heat rejuvenation treatment.
As the core hot section components in gas turbine systems, the turbine blades are inevitably subjected to various microstructure creep damages after long time service, which seriously affect their service life. The hot isostatic pressing(HIP)-combined rejuvenation heat treatment process has been developed as a critical step in refurbishment of degraded blades with equiaxed structure, and there is a common view that HIP process has positive impact on healing creep cavities, however, the turbine blades in current gas turbine systems are widely made of directionally solidified superalloys with excellent resistance of creep voids due to the minimal number of oriented grain boundaries, which indicates that it is likely to use simple re-heat rejuvenation treatment consisting of solution and ageing treatments as a cheaper refurbishment method in recovering microctructures and properties of directionlly solidified superalloys. In this work, the interrupted creep test was conducted on directionlly solidified GTD111 superalloy to simulate the service damage of turbine blades. The effect of re-heat rejuvenation treatment on γ ′ precipitates microstructure of creep degraded GTD111 superalloy and the evolution process of γ ′ precipitates under different stages of re-heat rejuvenation treatment were investigated. The results show that solid solution treatment at the temperature range of 1180～1220 ℃ can effectively dissolve the coarsened and rafted primary γ ′ precipitates and promote uniform precipitation of fine size secondary γ ′ precipitates in the damaged alloy, meanwhile the size of secondary γ ′ precipitates decreases with the increase of solution temperature and cooling rate. However, when the solid solution temperature increases to 1240 ℃,incipient melting in the interdendritic region ocurrs. High temperature ageing results in continued growth of the secondary γ ′ precipitates and precipitation of tertiary γ ′ precipitates. The size and cubic degree of the secondary γ ′ precipitates increase with the increase of ageing temperature and soaking time. The tertiary γ ′ precipitates continue to precipitate and grow during low temperature ageing process. The suitable re-heat rejuvenation parameters are 1220 ℃, 2 h, AC+1121 ℃, 2 h, AC+843 ℃, 24 h, AC. The rupture life of rejuvenated alloy under the condition of 750 ℃ and 843 MPa is up to 65 h, which is about 1.3 times of that of virgin alloy, due to its more volume fraction of duplex size γ ′ precipitates after re-heat rejuvenation treatment.
引文
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[5]Tawancy H M,Al-Hadhrami L M.Comparative performance of turbine blades used in power generation:Damage vs.microstructure and superalloy composition selected for the application[J].Eng.Fail.Anal.,2014,46:76
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[11]Zhou Y,Zhang Z,Zhao Z H,et al.Effects of HIP temperature on the microstructural evolution and property restoration of a Nibased superalloy[J].J.Mater.Eng.Perform.,2013,22:215
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[13]Lindblom Y.Refurbishing superalloy components for gas turbines[J].Mater.Sci.Technol.,1985,1:636
[14]Baldan A.Rejuvenation procedures to recover creep properties of nickel-base superalloys by heat treatment and hot isostatic pressing techniques[J].J.Mater.Sci.,1991,26:3409
[15]Kim H I,Park H S,Koo J M,et al.Microstructural investigation of GTD 111DS materials in the heat treatment conditions[J].J.Mech.Sci.Technol.,2012,26:2019
[16]Guo H M,Zhao Y S,Zheng S,et al.Effect of hot-isostatic pressing on microstructure and mechanical properties of second generation single crystal superalloy DD6[J].J.Mater.Eng.,2016,44(10):60(郭会明,赵云松,郑帅等.热等静压对第二代单晶高温合金DD6显微组织和力学性能的影响[J].材料工程,2016,44(10):60)
[17]Ruttert B,Bürger D,Roncery L M,et al.Rejuvenation of creep resistance of a Ni-base single-crystal superalloy by hot isostatic pressing[J].Mater.Des.,2017,134:418
[18]Mclean M,Tipler H R.Assessment of damage accumulation and propertiy regeneration by hot isostatic pressing and heat treatment of laboratory-tested and service exposed IN738LC[A].Proceedings of Superalloys[C].London:AIME,1984:73
[19]Pal J,Srinivasan D,Cheng E.Effect of rejuvenation heat treatment and aging on the microstructure evolution in Rene N5 single crystal Ni base superalloy blades[A].Superalloys 2016:Proceedings of the 13th International Symposium on Superalloys[C].Pennsylvania:TMS,2016:285
[20]Yao Z,Degnan C C,Jepson M A E,et al.Effect of rejuvenation heat treatments on gamma prime distributions in a Ni based superalloy for power plant applications[J].Mater.Sci.Tech.,2013,29:775
[21]Kuipers J,Wiens K,Ruggiero B.Rejuvenation heat treatment of single crystal gas turbine blades[A].ASME Turbo Expo 2017:Turbomachinery Technical Conference and Exposition[C].Charlotte:International Gas Turbine Institute,2017,6:1
[22]Cheruvu N S,Swaminathan V P,Kinney C D.Recovery of microstructure and mechanical properties of service run GTD-111 DSbuckets[A].ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition[C].Indianapolis,Indiana:International Gas Turbine Institute,1999,4:1
[23]Yoo K B,Lee H S.The microstructure and mechanical properties of Ni-based superalloy after service exposure in gas turbine[J].Mater.Sci.Forum,2010,654-656:2523
[24]Lee H S,Kim D H,Kim D S,et al.Microstructural changes by heat treatment for single crystal superalloy exposed at high temperature[J].J.Alloys Compd.,2013,561:135
[25]Semiatin S L,Kramb R C,Turner R E,et al.Analysis of the homogenization of a nickel-base superalloy[J].Scr.Mater.,2004,51:491
[26]Ning L K,Zheng Z,Jin T,et al.Effect of heat treatments on the microstructure and property of a new nickel base single crystal superalloy[J].Acta Metall.Sin.,2014,50:1011(宁礼奎,郑志,金涛等.热处理对一种新型镍基单晶高温合金组织与性能的影响[J].金属学报,2014,50:1011)
[27]Chen H,Dong J X,Zhang M C.Effect of heat treatment process on microstructure of cast superalloy K480[J].Trans.Mater.Heat Treat.,2012,33(7):37(陈昊,董建新,张麦仓.热处理工艺对铸造高温合金K480组织的影响[J].材料热处理学报,2012,33(7):37)
[28]Wu Q Y,Zhang J H,Sun X K,et al.Diffusion and solubilization of hydrogen in Ni-base single crystal superalloys[J].Acta Metall.Sin.,1996,32:938(吴秋允,张静华,孙秀魁等.氢在镍基单晶高温合金中的扩散和溶解[J].金属学报,1996,32:938)
[29]Baldan A.Review progress in ostwald ripening theories and their applications to nickel-base superalloys Part I:Ostwald ripening theories[J].J.Mater.Sci.,2002,37:2171
[30]Kusabiraki K,Nagahama H,Wang L,et al.The growth ofγ′precipitates in nickel-base superalloys[J].Tetsu Hagané,1990,76:1341(草開清志,長浜秀信,王理等.ニッケル基合金に析出したγ'相の長[J].鉄と鋼,1990,76:1341)
[2]Feng Q,Tong J Y,Zheng Y R,et al.Service induced degradation and rejuvenation of gas turbine blades[J].Mater.China,2012,31:21(冯强,童锦艳,郑运荣等.燃气涡轮叶片的服役损伤与修复[J].中国材料进展,2012,31:21)
[3]Li H,Lou L H,Shi X J,et al.γ′coarsening and creep rupture property of DZ411(DSM11)superalloy[A].High Temperature structure Material for Power and Energy:the Proceedings of 11th China's Superalloy[C].Beijing:Metallurgical Industry Press,2012:392(李辉,楼琅洪,史学军,等.DZ411(DSM11)合金γ′粗化与持久性能[A].动力与能源用高温结构材料-第十一届中国高温合金年会论文集[C].北京:冶金出版社,2012:392)
[4]Lee B K,Song W Y,Han T K,et al.Change of microstructures of directionally solidified Ni base superalloy GTD-111 at high temperature[J].Solid State Phenom.,2006,118:65
[5]Tawancy H M,Al-Hadhrami L M.Comparative performance of turbine blades used in power generation:Damage vs.microstructure and superalloy composition selected for the application[J].Eng.Fail.Anal.,2014,46:76
[6]Hosseini S S,Nategh S,Ekrami A A.Microstructural evolution in damaged IN738LC alloy during various steps of rejuvenation heat treatments[J].J.Alloys Compd.,2012,512:340
[7]Lvova E,Norsworthy D.Influence of service-induced microstructural changes on the aging kinetics of rejuvenated Ni-based superalloy gas turbine blades[J].J.Mater.Eng.Perform.,2001,10:299
[8]James A.Review of rejuvenation process for nickel base superalloys[J].Mater.Sci.Technol.,2001,17:481
[9]Liburdi J,Lowden P,Nagy D,et al.Practical experience with the development of superalloy rejuvenation[A].ASME Turbo Expo2009:Power for Land,Sea,and Air[C].Orlando:International Gas Turbine Institute,2009,4:819
[10]Wangyao P,Homkrajai W,Krongtong V,et al.OM study of effect of HIP and heat treatments on microstructural restoration in cast nickel based superalloy,IN-738[J].J.Met.Mater.Miner.,2017,17:87
[11]Zhou Y,Zhang Z,Zhao Z H,et al.Effects of HIP temperature on the microstructural evolution and property restoration of a Nibased superalloy[J].J.Mater.Eng.Perform.,2013,22:215
[12]Wangyao P,Polsilapa S,Nisaratanaporn E.The application of hot isostatic pressing process to rejuvenate serviced cast superalloy turbine blades[J].Acta Metall.Slov.,2005,11:196
[13]Lindblom Y.Refurbishing superalloy components for gas turbines[J].Mater.Sci.Technol.,1985,1:636
[14]Baldan A.Rejuvenation procedures to recover creep properties of nickel-base superalloys by heat treatment and hot isostatic pressing techniques[J].J.Mater.Sci.,1991,26:3409
[15]Kim H I,Park H S,Koo J M,et al.Microstructural investigation of GTD 111DS materials in the heat treatment conditions[J].J.Mech.Sci.Technol.,2012,26:2019
[16]Guo H M,Zhao Y S,Zheng S,et al.Effect of hot-isostatic pressing on microstructure and mechanical properties of second generation single crystal superalloy DD6[J].J.Mater.Eng.,2016,44(10):60(郭会明,赵云松,郑帅等.热等静压对第二代单晶高温合金DD6显微组织和力学性能的影响[J].材料工程,2016,44(10):60)
[17]Ruttert B,Bürger D,Roncery L M,et al.Rejuvenation of creep resistance of a Ni-base single-crystal superalloy by hot isostatic pressing[J].Mater.Des.,2017,134:418
[18]Mclean M,Tipler H R.Assessment of damage accumulation and propertiy regeneration by hot isostatic pressing and heat treatment of laboratory-tested and service exposed IN738LC[A].Proceedings of Superalloys[C].London:AIME,1984:73
[19]Pal J,Srinivasan D,Cheng E.Effect of rejuvenation heat treatment and aging on the microstructure evolution in Rene N5 single crystal Ni base superalloy blades[A].Superalloys 2016:Proceedings of the 13th International Symposium on Superalloys[C].Pennsylvania:TMS,2016:285
[20]Yao Z,Degnan C C,Jepson M A E,et al.Effect of rejuvenation heat treatments on gamma prime distributions in a Ni based superalloy for power plant applications[J].Mater.Sci.Tech.,2013,29:775
[21]Kuipers J,Wiens K,Ruggiero B.Rejuvenation heat treatment of single crystal gas turbine blades[A].ASME Turbo Expo 2017:Turbomachinery Technical Conference and Exposition[C].Charlotte:International Gas Turbine Institute,2017,6:1
[22]Cheruvu N S,Swaminathan V P,Kinney C D.Recovery of microstructure and mechanical properties of service run GTD-111 DSbuckets[A].ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition[C].Indianapolis,Indiana:International Gas Turbine Institute,1999,4:1
[23]Yoo K B,Lee H S.The microstructure and mechanical properties of Ni-based superalloy after service exposure in gas turbine[J].Mater.Sci.Forum,2010,654-656:2523
[24]Lee H S,Kim D H,Kim D S,et al.Microstructural changes by heat treatment for single crystal superalloy exposed at high temperature[J].J.Alloys Compd.,2013,561:135
[25]Semiatin S L,Kramb R C,Turner R E,et al.Analysis of the homogenization of a nickel-base superalloy[J].Scr.Mater.,2004,51:491
[26]Ning L K,Zheng Z,Jin T,et al.Effect of heat treatments on the microstructure and property of a new nickel base single crystal superalloy[J].Acta Metall.Sin.,2014,50:1011(宁礼奎,郑志,金涛等.热处理对一种新型镍基单晶高温合金组织与性能的影响[J].金属学报,2014,50:1011)
[27]Chen H,Dong J X,Zhang M C.Effect of heat treatment process on microstructure of cast superalloy K480[J].Trans.Mater.Heat Treat.,2012,33(7):37(陈昊,董建新,张麦仓.热处理工艺对铸造高温合金K480组织的影响[J].材料热处理学报,2012,33(7):37)
[28]Wu Q Y,Zhang J H,Sun X K,et al.Diffusion and solubilization of hydrogen in Ni-base single crystal superalloys[J].Acta Metall.Sin.,1996,32:938(吴秋允,张静华,孙秀魁等.氢在镍基单晶高温合金中的扩散和溶解[J].金属学报,1996,32:938)
[29]Baldan A.Review progress in ostwald ripening theories and their applications to nickel-base superalloys Part I:Ostwald ripening theories[J].J.Mater.Sci.,2002,37:2171
[30]Kusabiraki K,Nagahama H,Wang L,et al.The growth ofγ′precipitates in nickel-base superalloys[J].Tetsu Hagané,1990,76:1341(草開清志,長浜秀信,王理等.ニッケル基合金に析出したγ'相の長[J].鉄と鋼,1990,76:1341)