Abstract: In order to enhance the energy density and energy gradient of conventional tungsten inert gas(TIG) arc, ensure a balanced heat input and avoid the dispersion of energy input, the hollow tungsten central negative pressure arc welding method is put forward, the hollow tungsten central negative pressure arc welding system is designed and established, components and operating methods of this system are systematically elaborated. The shape of hollow tungsten central negative pressure arc is observed by using high-speed video camera, the welding ablation experiments at fixed points is carried out, and then the morphology of welded joints of is analyzed. The experiment results refer that hollow tungsten central negative pressure arc can be established stably between the hollow tungsten and work-pieces under the action of the arc itself rigid. Compared to conventional TIG arc, hollow tungsten central negative pressure arc contracts along the radial direction, being binding shape on macro-morphology, the tip of hollow tungsten presents incandescent state. For the macro morphology of welded joints, the weld width becomes narrow, the weld depth becomes deep, and the weld has a better shape.

Key words: arc shape, hollow tungsten, hollow tungsten central negative pressure arc, macrostructure, pressure