Abstract:The welding effects of the 20mm thickness dissimilar high-purity Al alloys (AlCu0.5, AlSiCu, AlSi1) with 6061 Al alloy are investigated by electron beam welding. The organizational performances of the welding joints of the dissimilar aluminum alloys are improved by the addition of the Al-Si solders. It is indicated by the welding organizations analysis that the Si content in welding joint varies to the dosage of Al-Si solder, and the sensitivity of the welding crack is significantly influenced by the Si content. Crack defects are easy to form when the Si content is about 1% in the welding joint. The higher the Si content is, the smaller the sensitivity of the welding crack has, until there is no crack defect with enough content of Si. The hardness of welding joints is increased with the increase of the Si content. For different high-purity aluminum alloys which weld with 6061 aluminum alloy, the excellent microstructure and properties of welding joints can be achieved by the addition of the appropriate Al-Si solder pieces.