weld penetration

[justmental]

ok welded some aluminium today does this look right as to penetration its
3mm checker plate at 125amps 2.4mm tungsten and a 1.6mm 4043 filler rod and gas at 7ltr.
it was just but joint no chamfer. I broke it off while still hot.

 

[Rrunnach]

I would have used a 2.5mm filler wire, with at least a 2.5mm root gap, sheet has parted due to lack of root penetration.

With a good sound weld, sheet will tear before weld gives!!

 

[hotrodder]

As Runnach i'd have used 2.4mm wire for that personally but it's a personal thing in that you just need to feed more 1.6mm i.e. won't fix anything in of itself but makes the welding a bit easier for most people. Again it's a personal thing but the weld could be made with or without a root gap. The easiest is with a prep and no gap but who can be bothered preping 3mm... above 3mm either a prep or gap is needed and when you get thinner than 3mm good fit up with no prep is preferable imo



The circled spot shows pretty much what you're looking for with no root gap. There's an oxide line visible where the two pieces meet which is normal but can also be hiding nasties- the bit to the left of that it looks like there's voids or suckback where oxides have prevented complete fusion

Here's an extreme example which was done by welding very slowly with not enough amps...



You can just about make out where fusion occured by the difference in shade. There's a large 'butt cheek' caused by the back partially melting and oxidising lots which results in the edges repelling each other rather than fusing

There's links to some pics of the abuse* a sound weld should take and to a google preview of Gene Mathers 'The welding of aluminium and it's alloys' that goes into more detail here, post #8... http://www.mig-welding.co.uk/forum/showthread.php?t=35996&highlight=fatigue

*that example is with 1050 (pure) aluminium which is softer and a lot more ductile than treadplate (5754). Again, as Runnach the weakest part of a butt weld should be the HAZ next to the weld. The correct filler wire for 5754 is 5356 which'd make it easier to pass a bend test as 4043 is both softer (weaker) and more brittle

 

[justmental]

thanks for that Hotrodder i was clearing out my shed and thought i would have a play as i made so room on the bench again. (and got caught playing instead of tidying up).
i have some 5356 1.6mm will be getting some 2.4mm monday if Gwer have some in still waiting for some 1050 only orderd them a week ago .

 

[hotrodder]

I've pretty much given up getting anything other than gas from GWER... used to always pick up various consumables while waiting for the paperwork but i struggle to find anything to give them money for now- all the decent abrasives are tucked away behind the counter (shelves full of silverline tat) so you have to ask, it all ends up more complicated and drawn out than it should be and at least half the stuff i normally want turns out to be out of stock.

 

[justmental]

well i will be getting them from somewhere else if they dont have them monday.