pic: Weld Testing :D

[JamesCH95]

Originally Posted by MrBasse

If welded properly, the weld should be stronger than the base material.

That's impressive strength on aluminum, I'm kind of surprised it held up with that angled piece doing the bulk of the work.

Originally Posted by Dr.Gusta

1x2x.125 wall. If done correctly the weld should be stronger than the material you are welding.

This is not always true.

While the weld should be designed to be stronger than the base material, this isn't always the case. Frequently teams will make parts out of 6061-T6, but when welded 6061-T6 turns into 6061-T0, and the welding rod alloy (generally 4043) won't ever be as strong as the parent material, even if it's re-heat-treated. The weldment must be designed to take this into account.

The trick here is that the HAZ (heat affected zone) near the weld is still parent material thickness, but has been annealed by the welding process, and is thus weaker than it used to be. This is where most failures will occur. While the HAZ is not precisely the 'weld bead' itself, it is part of the weld in a holistic sense.

To address the 'bolts are always stronger than welding' stance some people have... It depends, on a lot of factors. They each have their place. To point out one specific example in FRC: welding the old C-Channel kit frames saved about 3lbs in brackets and fasteners and resulted in a stiffer, stronger chassis. The C-Channel was 5052 alloy, no heat-treatment and thus no strength loss when being welded.