QCr0.8/TC4薄板电子束焊接头组织及断裂路径

Microstructure and fracture path of electron beam welded joint of QCr0.8/TC4 sheet

关键词:  QCr0.8铬青铜  TC4钛合金  电子束焊接  组织  断裂

Key words:  QCr0.8 chromium-bronze  TC4 titanium alloy  electron beam welding  Microstructure  Fracture path

摘要:

对QCr0.8/TC4异种材料薄板进行了电子束对接焊接试验。采用光学金相、扫描电镜、能谱分析及X射线衍射相分析等方法,对接头组织结构及相组成进行了分析。并对接头进行了性能测试及断口形貌观察,分析了断裂性质,探讨了断裂路径。结果表明,焊缝由大量的γ-CuTi相、金属间化合物CuTi₂,CuTi₃及少量的铜基固溶体组成,且靠近铜合金侧存在一层20 μm左右的反应层,推测其可能为Ti₂Cu,CuTi,Cu₄Ti₃,Cu₂Ti,Cu₃Ti等多种金属间化合物混合层;QCr0.8/TC4的电子束对中焊接性较差,接头断裂发生在焊缝中心的粗晶区,呈明显的解理断裂特征,接头抗拉强度很低,仅为82.1 MPa。

Abstract:

Butted joints of sheet of QCr0.8 and TC4 were gained by electron beam welding.Microstructure and phase composition were investigated by means of optical microscope, scanning electric microscope, energy dispersive spectrometer and X-ray diffraction, as well as the tensile strength and fracture observation to discuss the fracture characteristic and path of the joints.The results showed that the weld was composed of large quantity of γ-TiCu phase, intermetallics of CuTi₂ and CuTi₃, and a small quantity of Cu-based solid solution.And beside the copper, there exists an about 20 μm thick layer of compounds, speculated to be composed of Ti₂Cu, CuTi, Cu₄Ti₃, Cu₂Ti, Cu₃Ti etc..The electron beam weldability between QCr0.8 and TC4 is dissatisfactory with focus onto the butt center line that the tensile strength is only 82.1 MPa, with cleavage fracture taking place in the coarse grain zone in weld center.