Wow...

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I've been trying to pass an overhead full-pen aluminum test on 3/8" plate for the past 4 days.  I'm using a Miller 350 alumasomething that has the profiler option.  So far,  90% of my bend tests have cracked out.  I've followed the procedure to the letter,  run faster,  slower,  angle of attacks is always at 5 degrees and I have the cleanest interpass preps around.  I've done a lot of different welds and positions,  and have never had this high of a failure rate before.  Interpass temp is below 200, wire the is 3/64, 35 volts,  420 ipm,  don't remember all the pulse settings,  but it's right on with the other guys.  Has anyone else had issues like these?Common sense in an uncommon degree is what the world calls wisdom.
Reply:Base? Filler? Gas?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:5086 I believe..  Not sure of the filler and 75/25 helium.Common sense in an uncommon degree is what the world calls wisdom.
Reply:Do a coupon in the flat-1g or whatever it's called and test that, to helprule out items outside the operator.....(and I judge you to be highly competent).??is any backing used?If no backing, then the root base can have oxidation problems.Blackbird
Reply:Hello Brainfarth, I'm going to try to include a link from ESAB that may address some of the issues that you can consider. One other consideration: do you feel that it is possible that you are overheating the coupons? You could be causing a considerable loss in tensile strength in the HAZ or even in the weld itself and when the bends are being performed they will yield at the weakest point and this fracturing/breaking may not reveal any visible defects, but if you could check the tensile strength of the weld coupon it might be revealed that the weld area is considerable softer and thus prone to yielding/cracking. Here is the link that you should read through. http://www.esabna.com/us/en/educatio...356-alloys.cfmaevald
Reply:I finally passed my tests.  I ended up adjusting my travel speed down a little,  dropping my forward angle to less than 5 degrees and cooling the plates with air down to around 100 degrees.  My bend tests still showed the welds,  but much smother than before.  The face took 6 passes ,  where as the root was at 3. Funny thing was that the root was considerably smoother than the face passes(this is after grinding and bending) .  The only difference that I can think of between the sides is that the root side welds were larger.  And I've been told that smaller multiple passes have a higher tensile strength.  But for this kind of test,  that does not work out well.Common sense in an uncommon degree is what the world calls wisdom.