Tensile-Shear and Fatigue Properties of Resistance and MIG Spot Welds of Some Aluminum Auto Body Sheet Alloys 750463
Tensile-shear static and fatigue tests were conducted on MIG (GMA) spot welds in various combinations of 2036-T4 and 5086-H32 sheet with thicknesses ranging from 0.035 in to 0.125 in. Both single-spot and double-spot coupons were welded for each alloy combination. Although the average weld diameter at interface did not vary much among the various alloy and thickness combinations, the static and fatigue strengths increased substantially as the overall thickness of the lap joints increased. Filler alloys 4043 and 5356 produced similar fatigue strengths. On a pound/spot basis, the single-spot coupons had slightly higher fatigue strengths than the double-spot ones.
Tests were also conducted on resistance spot welds in combinations of 2036-T4, 5056-O, 5056-H111, and 5052-H32 sheet having thicknesses of 0.035 in and 0.050 in. With fatigue load expressed in pounds, the 0.035 in thick sheet welds had very similar fatigue curves. The curve for the higher strength 5052 welds (0.050 in thick sheet) was substantially higher than for the thinner sheet. For the same sheet thickness and weld diameter, resistance spot welds gave slightly higher static strength than MIG welds. For 0.035 in thick 2036, the MIG spot welds had fatigue strengths (based on percent of static strength) similar to those of resistance welds.