Abstract: The vacuum electron beam welding process (EBW)is used to make the vacuum composite blank.Studied are the microstructure and properties of the EBW weld of the composite blank.The facts as follows are revealed via the study:the EBW weld of the blank presents a“nail-shaped”morphology;the weld HAZ is narrow,and free of any overheated zone,and mainly presents as non-complete re-crystallization zone;along with increase of the weld depth,the ferrite in the weld zone is decreased,the martensite increased,and the grain size reduced;the hardness of the weld zone is the highest,and that of the base metal zone is the lowest,and the former is getting greater along with increase of the weld depth.