摘要
针对大尺寸涡轮盘固溶后处理冷却速率受限的问题,以直径1500 mm的GH4706合金盘锻件为对象,研究了980℃固溶4 h后分别进行空冷(AA)、炉冷至825℃稳定化处理后空冷(FSA)、炉冷至825℃后空冷(FA)和炉冷至825℃后石棉冷却(FAs)4种固溶后处理对合金时效析出相演化特征及力学性能的影响。结果表明,降低980~825℃间的冷速,促进了晶界η相的析出和长大,消耗了Ni、Ti元素,抑制了大尺寸η相周围γ'/γ"相析出,形成了胞状组织;降低825~600℃间的冷速,显著加速了γ'/γ"相长大呈立方状;FSA、FA和FAs处理后胞状组织体积分数分别为4.1%、1.0%和1.8%。AA和FA处理基本不影响合金的室温拉伸性能,FSA处理小幅降低了合金的拉伸塑性,FAs处理大幅损害了合金的室温屈服强度。胞状组织加速了室温冲击时合金中裂纹的形成和扩展,造成FSA处理合金冲击韧性较AA处理降低64%。但胞状组织可阻碍合金650℃持久实验过程中裂纹扩展并抑制微孔长大聚集,提高了合金的持久寿命。FAs处理时由于大尺寸γ'/γ"相降低了合金强度,从而缩短持久寿命。FA处理使合金析出了适量的胞状组织,显著提高了合金持久寿命,同时保持良好的室温拉伸和冲击性能,具有优异的综合性能。
GH4706 alloy is used for industrial gas turbine disks owing to its excellent properties,in-cluding high creep resistance,tensile strength,toughness,and microstructural stability up to approximate-ly 650 ℃.However,the increasing weight and size of large turbine disks have limited the cooling rate following the solution treatment,which hinders the control of the microstructure and mechanical properties of large GH4706 alloy disks.Herein,four solution post-treatments were conducted on a 1500-mm-diameter disk manufactured from GH4706 alloy after being treated at 980 ℃ for 4 h:air cooling+air cool-ing(AA),furnace cooling to 825 ℃ and stabilization treatment followed by air cooling(FSA),furnace cool-ing to 825 ℃ followed by air cooling(FA),and furnace cooling to 825 ℃ followed by asbestos cooling(FAs).The evolution of precipitates during aging(including forγ'/γ"coprecipitation andηphase)and their effects on mechanical properties were analyzed.Results indicated that reducing the cooling rate from 980 ℃ to 825 ℃ promoted the precipitation and growth of theηphase,leading to Ni and Ti con-sumptions.This inhibitedγ'/γ"coprecipitation around the largeηphase,thereby favoring the formation of a cellular microstructure.Further reduction in cooling rate from 825 ℃ to 600 ℃ substantially accelerated the growth ofγ'/γ"coprecipitates into cubic forms.The volume fractions of the cellular microstructure in the FSA,FA,and FAs treatments were 4.1%,1.0%,and 1.8%,respectively.The AA and FA treatments had negligible effects on the tensile properties of GH4706 alloy at room temperature;meanwhile,the FSA treatment slightly decreased tensile ductility.The FAs treatment led to a notable reduction in yield strength at room temperature.In impact testing at room temperature,the cellular microstructure accelerat-ed crack initiation and propagation,resulting in a 64%lower impact toughness of GH4706 alloy for the FSA treatment compared to that for the AA treatment.However,during stress rupture testing at 650 ℃,the cellular microstructure effectively hindered crack propagation and the growth and aggregation of mi-cropores,thereby extending the rupture life.However,the FAs treatment reduced the rupture life due to strength loss caused by the largeγ'/γ"coprecipitates.The FA treatment fostered an optimal level of cellu-lar microstructure,thereby increasing the rupture life while maintaining excellent tensile and impact prop-erties at room temperature,demonstrating remarkable overall mechanical properties.
作者
王冲
王磊
段然
田强
黄烁
赵光普
WANG Chong;WANG Lei;DUAN Ran;TIAN Qiang;HUANG Shuo;ZHAO Guangpu(Key Laboratory for Anisotropy and Texture of Materials,Ministry of Education,School of Materials Science and Engineering,Northeastern University,Shenyang 110819,China;Gaona Aero Material Co.Ltd.,Beijing 100081,China)
出处
《金属学报》
北大核心
2025年第11期1638-1652,共15页
Acta Metallurgica Sinica
基金
国家重点研发计划项目No.2022YFB3705102。
关键词
GH4706
合金
固溶后冷却
胞状组织
冲击韧性
持久性能
GH4706 alloy
cooling after solution treatment
cellular microstructure
impact tough-ness
stress rupture property
