Any alloy welding experts.

Does anyone know if I will have problems welding some 2mm wall alloy tube with the Tig after tacking it in place with the MIG. Its one of those trial and error fit type jobs and it will be easiest (as it needs to be done on the Landrover) to tack it all together with the alloy wire in the mig before Tig'n it all together. My concern is I have done simillar with mild steel in the past only tacking together with MIG then Gas welding. Everytime Ive tried to gas weld over the Mig Tack its caused problems. I dont know why, It just has.

So will it be OK to Tig over what has been tacked with the MIG?

Thanks.
Steve.

Just make sure its clean before you tig it. Should be fine.

Al.

it should be nice and clean BEFORE it was tacked Al

grind em down with clean softy Steve, then do all the usual gumpf and it'll be fine

Er, yeah. I just meant clean it after as well in case there is crap from the mig (soot or whatever).

Al

When I was a sheet metal worker eons ago, we used to use soap to stop ally sticking to soft pads (many tears). Is soap still used? If so does that affect the weld. Our welder used to gas weld and I think cleaned the ally with wire wool.

In case?! there'll be loads, in my experience.

It's called 'smut' believe it or not . 5356 is particularly bad for it, but easier to weld with. 4043 produces less smut but you need to run it in at a rate of knots - around twice the m/s wire speed, I've found. In either case, increasing the gas flow (pure Ar) helps a lot.

4043 leaves a weld that wont annodise because of the silicone content.........

(but its a nice easy grade to work with for the same reason)



easier to use flap sanders Alan - no cloggy, my fave cleaner for ally is a scotchpad material buffing wheel on a battery drill, quick and leaves a nice finish


I need to get out more

A stainless steel wire brush is preferred by the purists for preparing ali..............


I tend to use a 3M strip & Clean wheel on the air die grinder ..........separate wheels for Ali, SS, and Mild Steel.....





Ian

i wouldnt grind the ally where your going to weld,, compounds from the grinding disc will stay in the ally and will make your weld have black bits in it,, just use a file or grind then file.