激光增材制造高Nb含量GH4169合金微观偏析行为研究
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摘要
目的减轻不同热处理状态下激光增材制造高Nb含量GH4169合金组织中的微观偏析。方法采用激光增材制造方法对球磨Nb合金化后的合金粉末进行快速成形,获得具有较高Nb含量的GH4169合金试样。通过光学显微镜、扫描电子显微镜及能谱分析、维氏硬度测试方法,对沉积态、固溶态和直接时效态试样进行分析,研究因合金中Nb含量变化引起的微观偏析对沉积态和热处理态合金的枝晶组织和显微硬度的影响。结果随着Nb含量的增加,一方面,由于枝晶间的Nb含量增加,枝晶间(γ+Laves)共晶数量增加,且共晶组织形貌更为连续;沉积态试样的显微硬度由228.4HV增大至534.1HV。另一方面,枝晶干Nb元素含量增加,枝晶干与枝晶间Nb元素含量的差异缩小,Nb元素的偏析比由8.59减小至4.13。后续固溶处理后,枝晶结构逐渐消失,枝晶间Laves相的数量随之减少,枝晶干与枝晶间的微观偏析减轻;固溶态试样硬度值随之减小,减小趋势随固溶温度的升高而逐渐平缓。随着Nb含量的增加,直接时效处理后,各试样显微硬度值在微观区域内的均匀性提高,枝晶干与枝晶间强化相的析出差异减小。结论合适的热处理制度既可以实现合金元素的均匀化,还能减小枝晶干与枝晶间强化相的析出差异,减轻激光增材制造高Nb含量GH4169合金组织中的微观偏析。
The work aims to alleviate dendritic segregation of Nb modified GH4169 superalloy fabricated by laser additive manufacturing(LAM) after different heat treatments. Nb powders were added to the original GH4169 superalloy powder by ball milling, and the alloying GH4169 samples with high Nb content were fabricated by LAM. The as-deposited, solid solution and direct aging(DA) samples were analyzed by optical microscopy(OM), scanning electron microscopy(SEM), energy spectrum analysis(EDS) and Vickers hardness test. The effects of dendritic segregation caused by Nb content in LAM alloying GH4169 superalloy on microstructure and microhardness of as-deposited and heat treated sample were studied. On the one hand, the addition of Nb made the dendrite structure more obvious, and promoted the precipitation of γ+Laves interdendritic eutectics, and the morphology of γ+Laves interdendritic eutectics was gradually like net. With the increase of Nb content in LAM alloying GH4169 superalloy, the hardness value could reach 534.1 HV from 228.4 HV. On the other hand, the content of Nb in the dendrite core increased and the differences between dendrite core and interdendrite decreased, which made the segregation ratio decreased from 8.59 to 4.13. After solution treatment, the dendrite structure characteristics of the sample disappeared obviously with the rise of heat treatment temperature. The quantity of Laves phase between dendrites decreased and the microhardness value decreased because of the different degree dissolution of the Laves phase, showing the alleviation of dendritic segregation of LAM alloying GH4169 superalloy. The decreasing trend gradually dwindled with the increase of solution temperature. With the increase of Nb content, the microhardness uniformity of samples after aging treatment was improved and the difference of precipitation of strengthening phases in dendritic structure reduced. Suitable heat treatment can not only make alloying elements homogenized, but also reduce the difference of precipitation of strengthening phases in dendritic structure, and alleviate the dendritic segregation in LAM alloying GH4169 superalloy.
The work aims to alleviate dendritic segregation of Nb modified GH4169 superalloy fabricated by laser additive manufacturing(LAM) after different heat treatments. Nb powders were added to the original GH4169 superalloy powder by ball milling, and the alloying GH4169 samples with high Nb content were fabricated by LAM. The as-deposited, solid solution and direct aging(DA) samples were analyzed by optical microscopy(OM), scanning electron microscopy(SEM), energy spectrum analysis(EDS) and Vickers hardness test. The effects of dendritic segregation caused by Nb content in LAM alloying GH4169 superalloy on microstructure and microhardness of as-deposited and heat treated sample were studied. On the one hand, the addition of Nb made the dendrite structure more obvious, and promoted the precipitation of γ+Laves interdendritic eutectics, and the morphology of γ+Laves interdendritic eutectics was gradually like net. With the increase of Nb content in LAM alloying GH4169 superalloy, the hardness value could reach 534.1 HV from 228.4 HV. On the other hand, the content of Nb in the dendrite core increased and the differences between dendrite core and interdendrite decreased, which made the segregation ratio decreased from 8.59 to 4.13. After solution treatment, the dendrite structure characteristics of the sample disappeared obviously with the rise of heat treatment temperature. The quantity of Laves phase between dendrites decreased and the microhardness value decreased because of the different degree dissolution of the Laves phase, showing the alleviation of dendritic segregation of LAM alloying GH4169 superalloy. The decreasing trend gradually dwindled with the increase of solution temperature. With the increase of Nb content, the microhardness uniformity of samples after aging treatment was improved and the difference of precipitation of strengthening phases in dendritic structure reduced. Suitable heat treatment can not only make alloying elements homogenized, but also reduce the difference of precipitation of strengthening phases in dendritic structure, and alleviate the dendritic segregation in LAM alloying GH4169 superalloy.
引文
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[10]ZHU L,XU Z F,GU Y F.Effect of laser power on the microstructure and mechanical properties of heat treated Inconel 718 superalloy by laser solid forming[J].Journal of alloys and compounds,2018,746:159-167.
[11]KNOROVSKY G A,CIESLAK M J,HEADLEY T J,et al.Inconel 718:a solidification diagram[J].Metallurgical and materials transactions A,1989,20(10):2149-2158.
[12]SUI S,CHEN J,MA L,et al.Microstructures and stress rupture properties of pulse laser repaired Inconel 718 superalloy after different heat treatments[J].Journal of alloys and compounds,2019,770:125-135.
[13]SUI S,CHEN J,ZHANG R,et al.The tensile deformation behavior of laser repaired Inconel 718 with a nonuniform microstructure[J].Materials science and engineering A,2017,688:480-487.
[14]SUI S,CHEN J,MING X L,et al.The failure mechanism of 50%laser additive manufactured Inconel 718 and the deformation behavior of Laves phases during a tensile process[J].The international journal of advanced manufacturing technology,2017,91(5-8):2733-2740.
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[17]DU J H,LV X D,DENG Q,et al.High-temperature structure stability and mechanical properties of novel 718superalloy[J].Materials science and engineering A,2007,425-426(15):584-591.
[18]DU J H,LV X D,DENG Q,et al.Microstructure and mechanical properties of novel 718 superalloy[J].Acta metallurgica sinica(english letters),2006,19(6):418-424.
[19]LIU F C,LIN X,ZHAO W W,et al.Effects of solution treatment temperature on microstructures and properties of laser solid forming GH4169 superalloy[J].Rare metal materials and engineering,2010,39(9):1519-1524.
[20]刘奋成,林鑫,余小斌,等.激光立体成形GH4169合金再结晶过程中的界面和晶体取向演化[J].金属学报,2014,50(4):463-470.LIU Fen-cheng,LIN Xin,YU Xiao-bin,et al.Evoluton of inerface and crystal orientation of laser solid formed GH4169 superalloy during recrystallization[J].Acta metallurgica sinica,2014,50(4):463-470.
[21]SCHNEIDER J,LUND B,FULLEN M.Effect of heat treatment variations on the mechanical properties of Inconel 718 selective laser melted specimens[J].Additive manufacturing,2018,21:248-254.
[22]MOSTAFA A,RUBIO I P,BRAILOVSKII V,et al.Structure,texture and phases in 3D printed in 718 alloy subjected to homogenization and hip treatments[J].Metals,2017,7(6):196-218.
[23]DENG D W,WANG C G,LIU Q Q,et al.Effect of standard heat treatment on microstructure and properties of borided Inconel 718[J].Transactions of nonferrous metals society of China,2015,25(2):437-443.
[24]AMATO K N,GAYTAN S M,MURR L E,et al.Microstructures and mechanical behavior of Inconel 718 fabricated by selective laser melting[J].Acta materialia,2012,60(5):2229-2239.
[25]KOU S.Welding metallurgy[M].New Jersey:John Wiley&Sons Incorporated,2003.
[26]OUYANG Y F,ZHONG X P,DU Y,et al.Enthalpies of formation for the Al-Cu-Ni-Zr quaternary alloys calculated via a combined approach of geometric model and miedema theory[J].Journal of alloys and compounds,2006,420(1-2):175-181.
[27]刘奋成.激光立体成形GH4169合金的组织和强化机理[D].西安:西北工业大学,2011.LIU Fen-cheng.Microstructures and strengthening mechanism of GH4169 superalloy fabricated by laser solid forming[D].Xi'an:Northwestern Polytechnical University,2011.
[28]余小斌,刘奋成,林鑫,等.电磁搅拌激光立体成形GH4169合金的组织和硬度分析[J].应用激光,2014,34(6):513-517.YU Xiao-bin,LIU Fen-cheng,LIN Xin,et al.Microstructure and hardness of GH4169 super alloy fabricated by electromagnetic stirring assisted laser solid forming[J].Applied laser,2014,34(6):513-517.
[29]QI H,AZERM,RITTER A.Studies of standard heat treatment effects on microstructure and mechanical properties of laser net shape manufactured Inconel 718[J].Metallurgical and materials transactions A,2009,40(10):2410-2422.
[2]庄景云,杜金辉,邓群,等.变形高温合金GH4169[M].北京:冶金工业出版社,2006:1-43.ZHUANG Jing-yun,DU Jin-hui,DENG Qun,et al.Wrought superalloy GH4169[M].Beijng:Metallurgical Industry Press,2006:1-43.
[3]林鑫,黄卫东.应用于航空领域的金属高性能增材制造技术[J].中国材料进展,2015,34(9):684-688.LIN Xin,HUANG Wei-dong.High performance metal additive manufacturing technology applied in aviation field[J].Materials China,2015,34(9):684-688.
[4]黄卫东.激光立体成形[M].西安:西北工业大学出版社,2007:1-15.HUANG Wei-dong.Laser solid forming[M].Xi'an:Northwestern Polytechnical University Press,2007:1-15.
[5]NI M,CHEN C,WANG X J,et al.Anisotropic tensile behavior of in situ precipitation strengthened Inconel 718fabricated by additive manufacturing[J].Materials science and engineering A,2017,701:344-351.
[6]MOUSSAOUI K,RUBIO W,MOUSSEIGNE M,et al.Effects of selective laser melting additive manufacturing parameters of Inconel 718 on porosity,microstructure and mechanical properties[J].Materials science and engineering A,2018,735:182-190.
[7]YANG H H,YANG J J,HUANG W P,et al.The printability,microstructure,crystallographic features and microhardness of selective laser melted Inconel 718 thin wall[J].Materials and design,2018,156:407-418.
[8]BAMBACH M,SIZOVA I,SILZE F,et al.Hot workability and microstructure evolution of the nickel-based superalloy Inconel 718 produced by laser metal deposition[J].Journal of alloys and compounds,2018,740:278-287.
[9]刘奋成,林鑫,杨高林,等.不同气氛激光立体成形镍基高温合金Inconel 718的显微组织和力学性能[J].金属学报,2010,46(9):1047-1054.LIU Fen-cheng,LIN Xin,YANG Gao-lin,et al.Microstructures and mechanical properties of laser solid formed nickle basesuperalloy Inconel 718 preparedin different atmospheres[J].Acta metallurgica sinica,2010,46(9):1047-1054.
[10]ZHU L,XU Z F,GU Y F.Effect of laser power on the microstructure and mechanical properties of heat treated Inconel 718 superalloy by laser solid forming[J].Journal of alloys and compounds,2018,746:159-167.
[11]KNOROVSKY G A,CIESLAK M J,HEADLEY T J,et al.Inconel 718:a solidification diagram[J].Metallurgical and materials transactions A,1989,20(10):2149-2158.
[12]SUI S,CHEN J,MA L,et al.Microstructures and stress rupture properties of pulse laser repaired Inconel 718 superalloy after different heat treatments[J].Journal of alloys and compounds,2019,770:125-135.
[13]SUI S,CHEN J,ZHANG R,et al.The tensile deformation behavior of laser repaired Inconel 718 with a nonuniform microstructure[J].Materials science and engineering A,2017,688:480-487.
[14]SUI S,CHEN J,MING X L,et al.The failure mechanism of 50%laser additive manufactured Inconel 718 and the deformation behavior of Laves phases during a tensile process[J].The international journal of advanced manufacturing technology,2017,91(5-8):2733-2740.
[15]COZAR R,PINEAU A.Morphology ofγ?andγ?precipitates and thermal stability of Inconel 718 type alloys[J].Metallurgical transaction,1973,4(1):47.
[16]董建新,谢锡善,章守华.Inconel 718型合金中??和??的复合及单独析出对组织稳定性的影响[J].金属学报,1993,29(6):28-32.DONG Jian-xin,XIE Xi-shan,ZHANG Shou-hua.Influences of associated and separate precipitation ofγ?with??on thermal structure stability in Inconel 718 type alloys[J].Acta metallurgica sinica,1993,29(6):28-32.
[17]DU J H,LV X D,DENG Q,et al.High-temperature structure stability and mechanical properties of novel 718superalloy[J].Materials science and engineering A,2007,425-426(15):584-591.
[18]DU J H,LV X D,DENG Q,et al.Microstructure and mechanical properties of novel 718 superalloy[J].Acta metallurgica sinica(english letters),2006,19(6):418-424.
[19]LIU F C,LIN X,ZHAO W W,et al.Effects of solution treatment temperature on microstructures and properties of laser solid forming GH4169 superalloy[J].Rare metal materials and engineering,2010,39(9):1519-1524.
[20]刘奋成,林鑫,余小斌,等.激光立体成形GH4169合金再结晶过程中的界面和晶体取向演化[J].金属学报,2014,50(4):463-470.LIU Fen-cheng,LIN Xin,YU Xiao-bin,et al.Evoluton of inerface and crystal orientation of laser solid formed GH4169 superalloy during recrystallization[J].Acta metallurgica sinica,2014,50(4):463-470.
[21]SCHNEIDER J,LUND B,FULLEN M.Effect of heat treatment variations on the mechanical properties of Inconel 718 selective laser melted specimens[J].Additive manufacturing,2018,21:248-254.
[22]MOSTAFA A,RUBIO I P,BRAILOVSKII V,et al.Structure,texture and phases in 3D printed in 718 alloy subjected to homogenization and hip treatments[J].Metals,2017,7(6):196-218.
[23]DENG D W,WANG C G,LIU Q Q,et al.Effect of standard heat treatment on microstructure and properties of borided Inconel 718[J].Transactions of nonferrous metals society of China,2015,25(2):437-443.
[24]AMATO K N,GAYTAN S M,MURR L E,et al.Microstructures and mechanical behavior of Inconel 718 fabricated by selective laser melting[J].Acta materialia,2012,60(5):2229-2239.
[25]KOU S.Welding metallurgy[M].New Jersey:John Wiley&Sons Incorporated,2003.
[26]OUYANG Y F,ZHONG X P,DU Y,et al.Enthalpies of formation for the Al-Cu-Ni-Zr quaternary alloys calculated via a combined approach of geometric model and miedema theory[J].Journal of alloys and compounds,2006,420(1-2):175-181.
[27]刘奋成.激光立体成形GH4169合金的组织和强化机理[D].西安:西北工业大学,2011.LIU Fen-cheng.Microstructures and strengthening mechanism of GH4169 superalloy fabricated by laser solid forming[D].Xi'an:Northwestern Polytechnical University,2011.
[28]余小斌,刘奋成,林鑫,等.电磁搅拌激光立体成形GH4169合金的组织和硬度分析[J].应用激光,2014,34(6):513-517.YU Xiao-bin,LIU Fen-cheng,LIN Xin,et al.Microstructure and hardness of GH4169 super alloy fabricated by electromagnetic stirring assisted laser solid forming[J].Applied laser,2014,34(6):513-517.
[29]QI H,AZERM,RITTER A.Studies of standard heat treatment effects on microstructure and mechanical properties of laser net shape manufactured Inconel 718[J].Metallurgical and materials transactions A,2009,40(10):2410-2422.
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