Abstract: The challenges of significant weight reduction have promoted a focus on selection of light-weight materials. That is the reason that high strength aluminum alloy is becoming widely recognized as the candidates to replace steel. In order to develop proper post weld heat treatment process of 2A14 high strength aluminum alloy welded by electron beam, the effects of post weld heat treatment on microstructure and mechanical properties of 2A14 aluminum alloy welded joint are studied by using optical microscope (OM), scanning electron microscope (SEM), hardness test and tensile test. The results showed that the eutectic structure of the grain-boundary dissolved into the matrix gradually, dispersion-strengthening phase precipitated in weld zone and the hardness of weld seam increased obviously after post weld heat treatment. The tensile strength of the weld seam increased from 355 MPa to 465 MPa, even larger than the base metal. The fracture analysis show the dimples became deeper and the fracture location is all in weld seam, which proposes that the toughness of the weld increased.

Key words: Electron beam welding, Heat treatment, High strength aluminum alloy, Mechanical properties, Microstructure