The mechanical performance of 1 ¾-in. (44 mm) 5083-0 weldments was examined at room temperature and at -320°F (-196°C). The welds were made using 5183 and 5356 electrodes and three variations of the gas metal arc process; these were a twenty-pass vertical procedure, a two-pass high-current flat position method, and a one-pass vertical electrogas technique. It was determined that the tensile and yield strengths of the entire weldments, heat-affected zones and weld metals increased with decreasing test temperature. Both 5356 and 5183 filler alloys produced welds which met the existing codes and specifications; however, 5183 was preferred because it resulted in slight increases in strength with no sacrifice in ductility or toughness. In comparison with multipass welding, the high-current method produced welds with low defect levels and, therefore, higher tensile strengths and elongations. The high-current and electrogas weld yield strengths were respectively less due to coarser microstructures. The notch sensitivity and resistance to a propagating crack were slightly lower for weld metal than for the base plate or heat-affected zone at -320°F. This trend was particularly evident for the high-current welds. However, the toughness of all 5083-0 welds was indicated to be high, and structural failures would be unlikely to occur at elastic stresses unless cracks were very large.