Application of rotating arc system to horizontal narrow gap welding

A rotating arc system for narrow gap horizontal welding was developed for solving the problem that the molten pool sagged due to the gravity. The characteristic of the system was that the synchronous rotation of nozzle and wire was generated by eccentric sleeve driven by motor. This process not only may reduce welding effective heat input due to an increase in the welding instantaneous velocity but also may disperse arc force which could counteract the gravity of upper side of molten metal. Both the two aspects were beneficial for horizontal weld formation. Experimental results indicated that shapely horizontal joint could be obtained in appropriate rotating parameters. The asymmetry of joint formation indicated that the heat affected zone width and microstructure in upper side were larger than that in lower side. The effective heat input difference near each side caused by the instantaneous velocity difference was the main reason why the formation characteristics occurred.