Abstract: This is an experimental research to compare the welding characteristics of nickel-base high-temperature alloys welded by tandem electric beam welding (EBW)with that welded by single electric beam welding (SEBW).The strength of the welding zones (WM, HAZ, WJ, BM) is evaluated by means of testing micro size specimen on the experimental process.The influence of the different post-welded heat treatments on the mechanical properties of forged 718 alloys and the sensitivity of producing "Crystal boundary liquidization" in the HAZ are presented.