question on aluminum alloy

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So I have these old sheets of aluminum, 3/16" from who knows when. I took it to a guy to try and bend it but it just broke. Can 3/16" be bent usually in sheet form? we were trying to put a 90 degree bend in it. So I assumed it might be 70 series aluminum. I was told that 7075 couldn't be welded. I flapped and acetoned a spot and test welded it. Super dirty still but it welded fine. So it must not be 7075????
Reply:Not weldable does not indicate that you can't run a bead on it.  When they say that it is unweldable it means more so that when you try to join separate parts, there is an extremely high chance of cracking after the fact.
Reply:It is most probably 6061-T6. It will break unless it is softened to T-4 and a large punch used. 7075 could have cracked your weld. You can weld edges where there is no pulling, but that is it on 7075.Last edited by shovelon; 01-14-2015 at 08:01 PM.Weld like a "WELDOR", not a wel-"DERR" MillerDynasty700DX,Dynasty350DX4ea,Dynasty200DX,Li  ncolnSW200-2ea.,MillerMatic350P,MillerMatic200w/spoolgun,MKCobraMig260,Lincoln SP-170T,PlasmaCam/Hypertherm1250,HFProTig2ea,MigMax1ea.
Reply:ok. I will cut some coupons tonight and do some fillets and full pen splices and hammer on it to see if it cracks. And run some beads together so it stays hot and see if it cracks. I mig welded a piece last summer and it cracked, but it was weld on top of weld on top of weld. I never gave it a chance to cool.
Reply:Im scraping that aluminum. I ground it down and it is full of porosity. not worth screwing with. And I think its 6061 fwiw. $.30 on the dollar at the scrap yard!
Reply:6061 is good stuff to weld on. Not so much bending
Reply:You're probably using to small a bottom die,  if your bending it at to tight a radius then its going to want to crackVantage 500's LN-25's, VI-400's, cobramatics, Miller migs, synch 350 LX, Powcon inverters, XMT's, 250 Ton Acurrpress 12' brake, 1/4" 10' Atlantic shear,Koikie plasma table W/ esab plasmas. marvel & hyd-mech saws, pirrana & metal muncher punches.