The Institute of Plasma Physics, Hefei Institutes of Physical Science has developed a large-scale vacuum electron beam welding (EBW) system, including China Fusion Engineering Test Reactor (CFETR) vacuum vessel collar as a pre-research part completed by this system, and it has passed the expert acceptance test recently.

The acceleration voltage of the system is 150 kV, with the rated power 60 kW, and the volume of vacuum vessel is 66.5 m³. The single-welding of 160 mm Austenitic stainless steel 316 L and 32 mm oxygen-free copper TU1 can be carried out without groove. The pre-research collar composed of Austenitic stainless steel 316 L is about 4.2 m multiply by 2.7 m in dimension, and contains different welding thickness, 50 mm, 60 mm, and from 50 mm to 160mm variable cross-section welding line.

With the intact surface after welding, the welding quality meets EN ISO 13919-1: 1996 Quality Level B Standard.

The completion of the EBW system and the breakthrough of welding technology of CFETR vacuum vessel collar demonstrate the ability of ASIPP in electron beam welding of large welding components, which lays the technical foundation for the future collar welding in CFETR vacuum vessel, and provides a solution for welding new, refractory and dissimilar materials used in CFETR.

Meanwhile, the application of welding technology in sophisticated industries at domestic and abroad could be realized.

Vacuum electron beam welding has a series of advantages of high power density, strong beam penetration ability, large ratio of weld depth-to-width and little welding deformation. It is especially suitable for welding of large-thickness component, titanium and titanium alloys, copper and copper alloys, aluminum and aluminum alloys, magnesium alloys, refractory materials such as zirconium, niobium, Mo, tungsten, copper steel, titanium steel, nickel niobium and other dissimilar materials and precision components.