Helium arc welding method for casting beryllium-aluminum alloy

The invention provides a helium arc welding method for a casting beryllium-aluminum alloy. The helium arc welding method comprises the steps that pre-welding treatment, crevasse forming, surface polishing and cleaning are conducted on a workpiece before welding; the workpiece is preheated before welding; welding wire preparing, selecting and treating before welding are conducted; a 300 type argon arc welding machine is used, and helium protection is adopted for welding; and the welded workpiece is slowly cooled in a muffle furnace, single-face welding and double-face forming can be achieved, and the welding strength is basically equivalent to that of base metal. During helium arc welding of the casting beryllium-aluminum alloy, due to the fact that ionization voltage (used for measuring ionization energy) of helium gas is higher than that of argon gas, helium arc welding is higher in energy density and welding depth, single-face welding and double-face forming can be achieved for a steel plate with the thickn