Process And Mechanism Research Of Welding-Brazed TA2 Pure Titanium To 2024 Alumimum Alloy Joint Based On Space Electron Beam Heat Source

In present paper, TA2 pure titanium was successfully joined to 2024 aluminum alloy by welding-brazing method with a space electron beam heat source. The welding-brazing experiments without and with filler wire were carried out respectively, and the impacts of welding parameters to microstructure and mechanical properties were also studied. Using the optimizing parameters, a superior joint with good weld formation and high strength was obtained.The electron beam offset and welding energy input of self-melting brazing process were also studied respectively. When the electron beam offset was 0.3 mm,the molten 2024 aluminum alloy metal can wet and spread to TA2 pure titanium smoothly. The melting quantity of TA2 can be controlled, which can avoid forming too much brittle Ti-Al intermetallic compound. Tensile strength of the joint was 184 MPa. The welding energy input was adjusted by changing welding speed to control the thickness of reaction layer. When the welding energy input was 74.3 J/mm, the thickness of reaction layer was 4 μm. There are many bud intermetallic compound grew into weld. Tensile strength of the joint was 189 MPa due to pinning effect of the bud intermetallic compound.The welding-brazing process with filler wire was carried out to improve the appearance of back weld. The welding energy input, electron beam offset and joint gap were studied respectively. When the welding energy input was 90 J/mm, both sides of the joint were good formation. The tensile strength of the joint was 209 MPa. When the electron beam offset was 0 mm, the molten filler metal wetted and spreaded to TA2 and 2024 Al, which can control the melting quantity of TA2. The tensile strength of the joint was 236 MPa. When the joint gap was 0.4 mm, the thickness of reaction layer was 2 μm. Long striped and “H” shape Ti Al3 intermetallic compound dispersed distributed in weld. Those Ti Al3 intermetallic compound improved the tensile strength of the joint to 316 MPa w ith pinning effect.A finite element modelling was established by MSC.Marc finite element software. The temperature fields and stress fields of TA2/2024 Al joint duringwelding-brazing process was simulated. The method of welding-brazing with filler wire can improve the distribution of temperature fields and keep the melting pool size. It also can avoid burning-off at the end of welding by decreasing the heat accumulation. The residual drawing stress in the weld zone droped from 370 MPa to210 MPa, so the joint strength was increased.