METHOD FOR ELECTRON BEAM WELDING WITHOUT BACKING PLATE

The present invention relates to an electron beam welding method without a backing plate and more specifically, to an electron beam welding method without a backing plate, which can obtain excellent bonding effect even without a backing plate by performing a second welding on one surface of a base material after a first welding on the other surface of the base material. Provided is an electron beam welding method without a backing material, in particular, an electron-beam butt welding which makes the base materials to abut and to be bonded with each other and includes a first welding step performing an electron beam welding on the surface of the base material with a melting width of 2.5 to 3.5 mm over the entire welding depth; and a second welding step performing the electron beam welding on the other surface of the base material by 20 to 40% of the entire welding depth with a melting width wider than the melting width in the first welding step. Therefore, the present invention can reduce post-treatment without inconvenience of removing a backing material after the electron beam welding.