Weld size for 2mm thick aluminium extrusions

[James Braithwaite]

Hi there,

I'm a bit stuck specifying a weld size (bead throat) for a design I'm working on.

The pieces to be welded are 2mm thick 6082 extrusions.

Strength calculations I've done indicate that a 1mm throat would suffice (using 5356 filler), however I have no idea what a reasonable minimum weld size is.

I have been taught that the size should be between approx. 0.6 and 0.8 times the material thickness.

I've seen a couple of examples of 2mm aluminium welded with quite thick welds, so it seems it is possible to exceed the 0.8*t rule of thumb without burning a hole in the extrusions...

I'm suggesting TIG welds as it seems to be the preferred method of welding thin aluminium (less heat penetration than MIG).

My questions are:
1) What is the minimum weld size (bead throat) that is achievable with TIG?
2) Is it safe to exceed the rule of thumb I mentioned above?

Thanks
James

 

[Richard.]

I don't see why it would be an issue to increase the size of the weld to accommodate for the process. A 1mm throat thickness filet joint is around a 1.5mm leg length. (Quite a small weld)
You should have a tolerance to work to as this is a Manual process. 0.2mm is tight for welding tolerance. Try and work to leg length and aim for 2-2.5mm this should equate to 1.4-1.8mm throat thickness (this is quite doable and is very close to your range of 60-80% of material thickness.