TWI

The development of orbital friction stir welding (FSW) technology for joining aluminium pipes for gas insulated power transmission lines (GIL) is described. The equipment is outlined: hydraulic unit, control panel, FSW head with steel wire rope and a guide ring clamped onto the pipe. The pipes were pressed into circular form with an expansion device prior to welding. Backing strip rings of aluminium and steel were fabricated. The tooling and means of closing the keyhole at the end of the weld are described. Welds made by orbital FSW were examined nondestructively using radiographic and ultrasonic techniques. Metallographic investigations were conducted. Mechanical properties were examined. The cost effectiveness of orbital FSW was compared with that of TIG welding.

3rd International Symposium, 27-28 Sep 2001, Session 1: Process Development 1, Paper 02