熔焊缺陷对镍基高温合金GH4065A疲劳行为的影响  

Effect of welding defects on fatigue behavior of Ni-base superalloy GH4065A

作　　者：李林翰 张继[1] 田成刚 杨姗洁 沈中敏 张文云[1] 张北江[1] LI Linhan;ZHANG Ji;TIAN Chenggang;YANG Shanjie;SHEN Zhongmin;ZHANG Wenyun;ZHANG Beijiang(High-Temperature Materials Research Institute,China Iron and Steel Research Institute Group,Beijing 100081,China;AECC Commercial Aircraft Engine Co.,Ltd.,Shanghai 201108,China)

机构地区：[1]钢铁研究总院高温材料研究所,北京100081 [2]中国航发商用航空发动机有限责任公司,上海201108

出　　处：《航空材料学报》2024年第4期85-95,共11页Journal of Aeronautical Materials

基　　金：国家重点研发计划项目(2022YFB3705102);国家科技重大专项项目(2017-VI-0015-0087,2017-VI-0018-0090)。

摘　　要：采用SEM和EBSD显微分析手段研究镍基变形高温合金GH4065A熔焊焊点的缺欠组织,并对比研究无焊点、有密排焊点和疏散排布焊点3种GH4065A带中孔薄板试样分别在低周和低高周复合疲劳载荷下的寿命差异和断裂方式差异。结果表明:焊点组织中存在未熔合孔洞、凝固裂纹和液化裂纹,是导致含焊点试样低周和低高周复合疲劳寿命大幅下降的主要熔焊缺陷。这些熔焊缺陷的存在使得疲劳裂纹从无焊点试样的中孔内表面处转为在焊点处优先形成,导致700℃/700 MPa低周疲劳寿命的下降幅度可达44%~83%。在600℃和700℃低高周复合载荷(静应力700 MPa+动应力100 MPa)下,熔焊缺陷不仅使得裂纹源从中孔内表面处转为在焊点处优先形成,也改变了裂纹扩展方式,增大了沿晶扩展倾向。这使得低高周复合疲劳寿命在两种温度下均大幅下降超过85%。由于密排焊点因距离中孔结构更近,密排焊点试样低周疲劳寿命低于疏散排布焊点试样,但这种焊点情况差异对低高周复合疲劳寿命的影响不大。The spot-welding defects of highly alloyed Ni-base superalloy GH4065A were investigated by using SEM and EBSD analysis methods.Effects of the welding defects on fatigue life and fracture behavior were studied by comparing thin plate samples with a central hole that were non-welded,densely welded and sparsely welded respectively.The results show that the lack-of-fusion defect,solidification crack and liquation crack are the main welding defects responsible for significant reductions in low-cycle fatigue life as well as combined low and high cycle fatigue life.These welding defects result in a transition of the fatigue crack initiation site from the inner surface of the central hole in the non-welded sample to the welding spot in the welded sample,leading to 44%-83%reductions in low-cycle fatigue life at 700℃/700 MPa.For the combined low and high cycle fatigue conditions(with a stress amplitude of 700 MPa for the low cycle loading part and 100 MPa for the high cycle loading part),the welding defects not only alter the site at which fatigue cracks initiate,but also make the crack propagation mode more intergranular.This results in dramatic decreases of over 85%in the fatigue life of welded samples at both 600℃and 700℃.Due to shorter distance between the welding spot and the central hole,densely-welded samples exhibit a slightly lower level of fatigue life under low-cycle loading conditions compared to sparsely welded samples.However,the fatigue life difference between them becomes negligible when subjected to combined low and high cycle loadings.

关 键 词：高温合金 疲劳 熔焊缺陷 裂纹萌生 裂纹扩展 断裂方式 

分 类 号：TG146.15[一般工业技术—材料科学与工程] V252.2[金属学及工艺—金属材料]