Electron beam welding experiments of titanium alloys with different vanadium content to stainless steel,as well as alpha titanium to stainless steel using vanadium sheets as filler metal and transition portion were carried out.Microstructures of the joints were examined by scanning electron microscope.The properties were evaluated by microhardness and tensile strength.It was shown that electron beam welding is not feasible due to the brittle Ti-Fe intermetallics with high hardness.Increase of vanadium content in base metal can restrain but can't avoid the formation of cracks.When vanadium content was too large,the joint was embrittled by FeTi compound with supersaturated V and also cracked after welding.Crack free joint was achieved by using vanadium transition portion which can prevent the contact of Ti and Fe elements.However,the formation of brittle σ intermetallics reduced the tensile strength of the joint,only up to 134MPa.
Wang Ting,Zhang Binggang,Chen Guoqing,Feng Jicai State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology,Harbin 150001,China
Electron beam welding was carried out between aluminum alloy and steel with Ag interlayer. Seam morphology, structure and mechanical properties of the joints were investigated with different action positions of the electron beam spot. The results show that with the increment of the beam offset to the silver side from the interface between silver and steel, the seam morphology was improved, and the porosity in the Ag interlayer vanished. A transition layer mainly composed of Ag2Al and Al eutectic was formed at the interface between silver and aluminum, and became thin and spiccato as the beam offset increased. When the beam offset was too large, two IMC layers composed of FeAl and FeAl3 respectively were formed at the interface between steel and Ag interlayer. The optimal beam offset was 0.2 mm, and the maximum tensile strength of the joint was 193 MPa, 88.9% that of the aluminum alloy, and the fracture occurred at the interface between steel and Ag interlayer.
