Physical and Thermal Processes During Electron Beam Welding

Complicated processes of the seam formation during electron beam welding are described. The physical processes in the weld pool and in the vapor-plasma mixture emitted in the cavity into the liquid metal created by intensive high energy beam are discussed. The dynamics of the liquid metal in the weld pool are interconnected with the energy distribution of the electron beam in the cavity which influences the weld depth and width and controls the defect formation in the weld such as pores (blow holes), non-uniformity of the weld root (spiking) and rippled weld surface. The moving heating source, working in the weld pool of metal samples is steady only as a first approximation due to the molten pool dynamics. A more exact heat model of the electron beam welding must take into account the unstable nature of beam transport within vapors and gas plasma in the cavity as well as the variations of energy dissipation on the crater walls and of heat transfer through molten metal of the weld pool.