aluminum penetration

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here's my try at building another espresso knock box.  4" square box, basically.  full-open corner welds. but i'm unclear on how full penetration on aluminum is suppose to look like.  there doesnt seem to be any heat marks on the inside of the welds.there's a couple of little spots inside the seams where there seem to be a little blur of something.  just wonderingif that's what it suppose to look like.help
Reply:well, google has been quite helpful lately.  found some more info on the back side of full penetration alu. over at the hobart forum.http://www.hobartwelders.com/weldtal...ad.php?t=30890
Reply:did u tig, push pull, or spoolgun?flat or downhand?“I'm going to do the thing that God put Galen Beasley on this Earth to do:Have Salon quality hair and weld.Nothing like a good cup of coffee and the smell of 6010 burning in the morning. 971-204-3444 cell API ASME Structural NDT and Repair
Reply:There won't be any heat marks with aluminium. If you can see the cut edges of the origional joint then you didn't get full pen.More examples in this thread... http://weldingweb.com/vbb/showthread.php?t=18625 I demoed some flaws as well as what the backside of a full pen Al butt looks like. Couple more threads on the same subject in the pics and projects forum, Zap had a try as did Gollum IIRC. Should come up with a search of the pics forumThe 'why we weld aluminium sheet with oxy fuel' thread has some examples in it too. Butt welds again though, with an outside corner the root side reinforcement has a similar texture but shape is slightly different due to the geometry of the partsAl behaves quite differently to steel/stainless (much lower melting temp and much higher heat conductivity), those spots you mention are where you've just melted the backside of the joint in a couple of places. With steel etc that's typically enough to get fusion but with aluminium unless you feed sufficient wire into the joint the edges tend to pull back rather than coalesce. With oxyfuel the flux is 'cleaning' and protecting the back of the joint preventing this so you need less wire to get fusion and the weld typically has less root reinforcement. Both my examples are a touch heavy on the root reinforcement i.e. can do better but there is a much finer line between success and failure than with say steel
Reply:Originally Posted by galencwidid u tig, push pull, or spoolgun?flat or downhand?
Reply:Im sure it will be more than strong enough for whatever you need, unless you were expecting the insides to look like they were welded together in which case your going to have a very hard time getting that result on an insde corner.Last edited by sn0border88; 03-23-2010 at 01:19 PM.Have we all gone mad?
Reply:sn0border, you're right, it is more then strong enough for what i need it for.  I have been using one i built with the same method and same half-penetrated welds.  The only other issue, two folds.  One, the tiny little gap is difficult to clean, and two, it looks "half done."it looks like i have a lot of homework to do.  gotta hit the welder as soon as i get home tonight.
Reply:Interestingly enough I was messing around working on a similar sized bit of aluminum just the other day.   Part was about 4" x 4".  Was just setting up a machine and playing around with it.These are mig welds though, not tig welds.Here are some tips on aluminum mig welding: mig welding aluminum