IMPROVED WELD STRENGTH IN 2000 SERIES ALUMINUM ALLOYS

The use of coolants during the welding of 2000 series aluminum alloys was investigated in an attempt to improve the properties of fusion welds in these alloys. The general premises behind this experimentation were that cooling combined with minimal welding heat inputs should narrow the heat-affected zones and should increase the quenching rates in both the weld bead and heat-affected zone. It was believed that beneficial effects on weld properties might be obtained in this way. A metallographic study of welds made with and without coolants indicated these postulates to be true. Weld heat-affected zones and zones of eutectic and grain boundary melting were narrowed, and dendritic structure in weld beads was refined when coolants were used. In addition, joint efficiencies of 90 or better were obtained for 2014-T6 sheet without solution treatment and both with and without artificial aging after welding. Joint efficiencies exceeding 85 were also obtained for 2024-T86 sheet without postweld solution treatment.