Questions about the back side of my TIG welds

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I have started on the bucket for the loader I'm building for my garden tractor and used 3/16 steel. Used my scratch start TIG and welded all the outside corners, no filler. Plan is to do the inside corners with 7018, mainly just to keep the moisture out of the joints. Inside of the bucket after welding the outside corners, I noticed all this white fuzzy, powdery crap. I've not ever noticed this before. Can somebody tell me what this is? Attached ImagesSafety 3rdGump
Reply:I'm probably way off, but I usually see that white powder when I am welding something galvanized. Are you sure that you've got plain steel?
Reply:Gump  -  Sugaring or carbide precipation, prevention requires back-purging, search those terms [book or Inter/Web].   Opus
Reply:Its not SS.Its the galv. burning off from the backside.
Reply:Yes it is galvanized sorry forgot to mention that. But, i did grind it off both sides of each piece before welding. Guess I shoulda done more grinding. Thanks guys. I've not welded galv before and didnt know it would do that. I do know about not breathing the smoke from it thoughSafety 3rdGump
Reply:Looks like you got it off good on the front.You will know when you haven't.
Reply:Gump  -  Oops on me; the white powder was the "tell",are you any relation to Forest?      Opus
Reply:The white powder is zinc oxide (ZnO).  In it's solid form, it's used as a food and drug additive, so not that dangerous, but one should avoid breathing it if it's airborne as dust.  Where it gets more dangerous is when it's in fume form (boiled zinc (from the extreme heat of the welding arc) combines with oxygen to form zinc oxide fumes).http://www.aws.org/technical/facts/FACT-25.pdfWhen you get it around a weld, it's fume that has condensed back to solid on surrounding surfaces.  Either mechanically remove the galvanizing farther back before welding or take adequate safety measures when welding and prepare for any post-cleaning of the condensed zinc oxide that may be present after welding.Also watch out for fumes when grinding or plasma/flame cutting galvanized.
Reply:Opus, no relation to forrest but we do have a lot in common, except I'm not a multi-millionaire, dont care for shrimp, never met the president,etc....Dbotos- thanks for all the infoSafety 3rdGump
Reply:Never had much luck TIG welding anything that was Galvanized........Stick weld or mig weld it and don't get sick breathing the fumes........Bad stuff... Your strength is going to come from an inside weld so don't waste all your time with tig on that bucket argon is too expensive to waste not to mention being slow.....Last edited by B_C; 07-24-2012 at 03:57 PM.  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:Just out of curiosity, where'd you get the 3/16" galvanized material?  I usually only see galvanized in thinner sheet metal gauges or finished products that have been galvanized after welding and/or forming.
Reply:Bought it out of the scrap pile at JB's Salvage over in Bloomington. I think it's actually 8 or 9 gauge. Havent mic'ed it but it's just a scosh under 3/16Thanks fer the pointers BC. As I said earlier, i aim to stick weld inside with 7018.  I wanted to practice my tig though so i tigged all the outside cornersLast edited by Gump; 07-24-2012 at 10:41 PM.Safety 3rdGump
Reply:Originally Posted by B_CNever had much luck TIG welding anything that was Galvanized........Stick weld or mig weld it and don't get sick breathing the fumes........Bad stuff... Your strength is going to come from an inside weld so don't waste all your time with tig on that bucket argon is too expensive to waste not to mention being slow.....