GH4720Li合金中温区低周疲劳行为研究  

Low-cycle fatigue behavior of GH4720Li alloy at intermediate temperature

作　　者：黄子琳 安腾 谷雨 唐超[2] 曲敬龙[2] 杜金辉[2] HUANG Zilin;AN Teng;GU Yu;TANG Chao;QU Jinglong;DU Jinhui(AECC Hunan Aviation Powerplant Research Institute,Zhuzhou 412000,Hunan,China;Beijing Key Laboratory of Advanced High Temperature Materials,Central Iron and Steel Research Institute,Beijing 100081,China)

机构地区：[1]中国航发湖南动力机械研究所,湖南株洲412000 [2]钢铁研究总院高温合金新材料北京市重点实验室,北京100081

出　　处：《钢铁研究学报》2021年第3期246-252,共7页Journal of Iron and Steel Research

基　　金：国家自然科学基金资助项目(51874103)。

摘　　要：奥氏体沉淀强化GH4720Li合金用于制备航空发动机涡轮盘,其服役条件下的疲劳性能是当前研究的热点。研究了GH4720Li合金在中温区(450和550℃)不同应变条件下的低周疲劳行为。结果表明,GH4720Li合金的剪切模量和杨氏模量随着温度的升高而不断降低,但是中温区的抗拉强度和屈服强度不随温度而剧烈下降。GH4720Li合金的低周疲劳寿命随着应变值的升高而降低。在550℃/0.9%最大应变值时,疲劳寿命存在一个"平台"而表现出极大的分散性,当最大应变值低于"平台"时,低周疲劳寿命随温度升高而升高。GH4720Li合金疲劳寿命的"平台"现象是因为样品表面裂纹萌生和内部裂纹萌生2种断裂失效模式的竞争导致。The precipitation strengthened nickel-based GH4720 Li alloy is an important high temperature structural materials for turbine discs.The fatigue behavior is a major concern of GH4720 Li disc superalloy due to its service condition.The low-cycle fatigue behavior of GH4720 Li alloy was studied at 450℃ and 550℃ at the maximum strain of 0.8%,0.9% and 1.0%,the stress ratio was 0.05 and the frequency was 0.33 Hz according to the service condition.The results show that the shear modulus and Young's modulus of GH4720 Li alloy decrease with the increasing temperature,however,the tensile strength and yield strength are not decreased sharply with the increasing temperature at intermediate temperature.The low-cycle fatigue life of GH4720 Li alloy decreases with the increasing strain value.The fatigue life has a"shelf"behavior which shows a great dispersibility at 550℃ and a maximum strain value of 0.9%.When the maximum strain value is lower than the"shelf",the low-cycle fatigue life increases with increasing temperature.The"shelf"behavior of the fatigue life in GH4720 Li alloy is the competitive fracture failure mode between surface crack initiation and internal crack initiation.The sample of fatigue life of GH4720 Li at the"shelf"zone failed by the internal crack initiation mechanism is 15 times that of the sample failed by the surface crack initiation mechanism.

关 键 词：GH4720Li合金 低周疲劳 中温区 裂纹萌生机制 

分 类 号：TG13.3[一般工业技术—材料科学与工程]