TWI

A comparative investigation was undertaken of MIG and friction stir welding of AW 6082-T6 alloys (Al, 0.63%Mg, 0.84%Si, 0.71%Mn) for marine applications such as structural panels in pontoons, and the welded joint microstructure and mechanical properties were analysed. Welding experiments were conducted to identify optimal parameters for both processes. MIG welds in 6 mm plate were made in a Y butt preparation using ER 5183 filler wire in three runs. FSW butt welds were made using a hardened steel tool with a threaded pin of MP 159 alloy. Microstructure was observed by optical microscopy and porosity levels were determined by x-ray diffraction. Porosity and lack of fusion were found in the MIG weld. Mechanical properties were characterised by microhardness measurements as well as tensile, bend and fatigue tests. Issues discussed include weld quality, the effect of operation temperature on hardness and tensile strength, and economic aspects such as investment and repair costs.

7th International Symposium, 20-22 May 2008, Poster Session, Paper 03