ZTC4钛合金精铸件电子束焊接接头组织与疲劳行为研究  

Study on Microstructure and Fatigue Behavior of Electron-beam Welding Joints of ZTC4 Titanium Alloy Investment Castings

作　　者：刘茜珂[1] 刘昌奎[1] 彭楚峰[2] 郑春红[3] 毛智勇[4] 

机构地区：[1]北京航空材料研究院,北京100095 [2]中国人民解放军驻成飞公司军事代表室,成都610092 [3]沈阳飞机设计研究所,沈阳110035 [4]北京航空制造工程研究所,北京100024

出　　处：《失效分析与预防》2008年第3期32-36,共5页Failure Analysis and Prevention

摘　　要：在四种不同应力水平下对ZTC4钛合金精铸件进行了疲劳试验,研究了ZTC4钛合金精铸件电子束焊接接头组织、疲劳性能与疲劳断裂特征。结果表明,ZTC4钛合金精铸件基体显微组织为片层组织,电子束焊缝为晶粒内析出大量的细针状α′相的针状马氏体组织特征;焊缝硬度略高于基体;疲劳裂纹一般起源于焊缝熔合区表面或次表面微气孔,疲劳扩展初期断口表面存在类解理光滑刻面,并且疲劳条带呈脆性条带特征,而在疲劳扩展的中后期,转变为韧性疲劳条带特征;尺寸较大的表面、次表面焊接或冶金缺陷对焊接接头的疲劳性能有较大的影响。Fatigue tests of ZTC4 titanium alloy investment castings were carried out under different stress levels of 340MPa, 400MPa, 460MPa and 520MPa. The microstructure, fatigue properties and fracture features of the electron-beam welding joints were investigated. The results show that the microstructure of the base material is lamellar structure. The microstructure of the welding joints is acicular martensite and there is a lot of aciculate a＇ phase in the grains. The microhardness of the welding joints is higher than that of the base material. The fatigue cracks initiated from gas cavities in the surface or subsurface of the fusion zone. There are some slick facets and brittle fatigue striations near the fatigue source region of the fracture surface, and there are ductile fatigue striations at the extension and final fracture regions. The larger welding or casting defects in the surface or subsurface layer have greater effect on the fatigue properties of the welding joints.

关 键 词：钛合金精铸件 电子束焊接 疲劳 断裂 

分 类 号：TG407[金属学及工艺—焊接]