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I am having problems achieving the 24 ksi minimum requirement for a tensile test and I have no idea what the problem could be. The break is ductile and in the parent material and not in the weld.Process: GTAWFiller: ER4043, 3/32" diameterPlate: 1/4" AA6061-T651Joint: Single bevel2 passes on side 1 and then gouging the back and adding 1 pass to side 2.It should be a simple test...visually the weld looks good. I don't think the heat affected zone would weaken the parent material that much...I am suspecting that it could be a bad batch of aluminum? Both tensile samples are only pulling at 20 ksi and breaking in the plate and not the weld...any help would be much appreciated.
Reply:Shawn, Im new at welding (well, only been at it about 6 months or so), but have done alot of reading. I know that T6 is heat treated 6061-t0. What I remember about this is that the T6 is achieved by air tempering, dont remember the exact temps, but I know that the it involves so many hours at such and such temp and then its allowed to air cool. So, Im thinking that the heat stress from welding both sides and doing the double pass and single pass (your making 3 passes with the torch over the same area of aluminum) is whats taking out most of the temper. Perhaps this is your test To see how you manage the heat to keep from taking the temper out of the aluminum. How about trying to weld in increments, perhaps bouncing from spot to spot thus distributing the heat uniformely and perhaps allowing a complete cooling after each pass. This is what I would try if time allowed.Various GrindersVictor Journeyman torch200cf Acet. 250cf oxygenLincoln 175 plus/alpha2 gunLincoln v205t tigLincoln 350mpEsab 650 plasmaWhen you can get up in the morning, Its a good day.Live each day like its your last.
Reply:What are you gouging out with??? I would avoid any type of grinder and go with a saw blade. Also the bevel angle on aluminum has to be much wider that steel. Are you welding into anything narrower than 90 degrees??? Also check the colour of your metal. I don't know much about tig multipass but on an aluminum boat the yard was doing TIG repairs over the MIG. An old hand showed me all the locations where the TIG welder had overheated. The area had a gray cast to it. He predicted future problems.
Reply:Stupid question - but have you tried tensile testing the plate before welding?
Reply:Something that lit up the dark recess of my minds was "age hardening". Are the test pieces being immediately tested or left for 24 hours? I am not sure about 6000 alloy having any age hardening effect. It's worth checking.
Reply:hi all,6061-T651 is heat treated and stress relieved. UTS around 45,000PSI. welding will result in (at least) partial annealing of the HAZ. the hotter it gets/longer it spends at high temps, the softer it becomes.6000 series does indeed age harden (not sure, but i think it makes about 60% recovery in a couple of days- as welded (with 4043) alcotec quotes around 27,000PSI). i've never done this test so am guessing as to whats permited here,...coupon size can affect how hot (and therefore how soft) the HAZ gets- remember, Al is a great conductor of heat.was there/should there be a max interpass temp?as lotechman said, were/should the coupons be aged before testing?however, i would of thought these points would be in the weld procedure, along with joint configuration etc.hope this helps
Reply:I would like to thank everyone for their responses. I will keep all your advices in mind. Your help is greatly appreciated.
Reply:let the sample sit for a week. when you weld it at all it's just been fully annealed, 6061 will gain strength back to about t3 over time (a few days or so) all by it's self. If you need more than about T3 it needs heat treated--- I hope i've summarized this accurately. here is a link to a lot of info.http://www.key-to-nonferrous.com/def...ID=Articles#p1 |
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发表于 2021-9-1 00:11:38