再热恢复处理对蠕变损伤定向凝固高温合金γ′相的影响  

Effect of Re-Heat Rejuvenation Treatment on γ′ Microstructure of Directionally Solidified Superalloy Damaged by Creep

作　　者：唐文书[1] 肖俊峰[1] 李永君[1] 张炯[1] 高斯峰[1] 南晴[1] TANG Wenshu;XIAO Junfeng;LI Yongjun;ZHANG Jiong;GAO Sifeng;NAN Qing(Xi'an Thermal Power Research Institute Co.,LTD.,Xi'an 710054,China)

机构地区：[1]西安热工研究院有限公司,西安710054

出　　处：《金属学报》2019年第5期601-610,共10页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目No.51601145~~

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 ag

关 键 词：定向凝固高温合金 蠕变损伤 再热恢复 γ′ 持久寿命 

分 类 号：TG132.32[一般工业技术—材料科学与工程] TG156.1[金属学及工艺—合金]