Study on Laser Welding of Case Closure Weld for ITER Correction Coil

ITER correction coil (CC) cases have characteristics of small section, large dimensions, and complex structure. The case welding deformation should be controlled within ±2 mm, and the case weld is required to meet the ISO 5817 class B. In order to achieve the requirements of weld, laser welding with hot wire was chosen for the closure welding of the CC case. The biggest advantage of the welding method is the small amount of heat input and small welding deformation. A series of welding experiments and a scaled trial with the same welding joint designed have been carried out and the preliminary welding specifications have been summarized. This paper introduces the prequalification of the case closure welding which describe the details like the welding groove design, the welding specification, and the results of the destructive and nondestructive test. As can be seen from the results, the welding quality and deformation are very close to the design requirements which may be helpful for the real qualification in the future.