Believe it or not, the data exists. Weld metal data for virtually all aluminum filler metals was developed in the 1960s. But you are correct that it is very difficult to find. None of the design or fabrication codes include it because weld metal data really is of little or no use when designing aluminum structures. The various codes have already established minimum tensile and shear strengths through extensive testing. In welding steel, the weld is often seen as the weak point in the weld, so the properties of the weld metal are important. However, in aluminum welding the weld is usually not the weak point of the weld; the material’s heat-affected zone (HAZ) is. Let’s look at specific cases. In welding non-heat-treatable alloys such as the 5XXX series, the HAZ of the weld will always be annealed to O temper properties. As long as you follow the code recommendations for selecting the filler metal, the weld properties will always be determined by the O temper properties of the welded material. That’s fine for welds that are stressed in tension—usually butt welds—but what about welds that are stressed in shear, such as fillet welds? All codes contain allowable shear strengths for the various filler metals. These shear strengths are almost always determined by extensive testing, so you should use them. Now let’s discuss the heat-treatable alloys, such as 6061 and the other 6XXX alloys. In welding these alloys the weld metal is almost always stronger than the material HAZ. The minimum tensile strength for butt welds is determined by the strength of the material HAZ, not the tensile strength of the filler metal. As an example, all codes require a minimum tensile strength of 24 KSI for welds in 6061-T6, regardless of which filler metal you use, despite the fact that the tensile strength of 5356 is significantly higher than that of 4043. What about welds that are stressed in shear? Again, the shear strength of all the filler metals has been determined already and is shown in the various codes. You should use these values. You can see that the strength of the filler metal itself is not really meaningful. Because of that, I’m not going to give it to you. By the way, although the shear strength of the filler metal is infrequently shown as a fraction of the all-weld metal tensile strength, do not use this method to estimate it. It is notoriously inaccurate and should not be used for design calculations.