I recently TIG butt welded 2 -1/8 inch 6061 plates in class. Butted tight together (misake?) got a perfect looking weld but
the weld cracked right down the middle. I asked instructor "what happened?" Reply "don't know" Don't think he was interested?
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- Otto Nobedder
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Weldmonger
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Posts:
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Joined:Thu Jan 06, 2011 11:40 pm
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Location:Near New Orleans
Welcome, Norm,
Let's analyze it a bit closer. You say, "butted tight". Was the joint beveled? Preferably to a knife-edge? What did the back side look like? If you don't get 100% penetration with a bit of push-through, the straight line of the joint from the back side is the perfect place for cracking to start.
Another common place for a crack to begin is where your weld stops. If you just call it done and stop, you tend to leave a significant crater, leaving a very thin bond (especially if you don't have full penetration), so it's very important on aluminum welds to hold the arc at the end and add filler a time or three as you tail off, so you don't have that crater.
What filler were you using? 4043 is common on 6061, but not always the best choice. 5356 is a better match to the properties. I also hear wonderful things about 4943, but I've not used it.
We'll be glad to help you sort this out.
Steve S
Let's analyze it a bit closer. You say, "butted tight". Was the joint beveled? Preferably to a knife-edge? What did the back side look like? If you don't get 100% penetration with a bit of push-through, the straight line of the joint from the back side is the perfect place for cracking to start.
Another common place for a crack to begin is where your weld stops. If you just call it done and stop, you tend to leave a significant crater, leaving a very thin bond (especially if you don't have full penetration), so it's very important on aluminum welds to hold the arc at the end and add filler a time or three as you tail off, so you don't have that crater.
What filler were you using? 4043 is common on 6061, but not always the best choice. 5356 is a better match to the properties. I also hear wonderful things about 4943, but I've not used it.
We'll be glad to help you sort this out.
Steve S
- DLewis0289
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Ace
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Joined:Sun May 01, 2016 7:46 am
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Location:Fort Myers Florida
Not accusing you lol, but when I taught I would catch the students pulling the plan B weave. They would not be happy with the look of their weld and throw the filler away and grab the torch with two hands and go back over the weld real quick with little circle or weaves to "dress it up" and I would see a lot of hair line cracks right down the center.
AWS D1.1 / ASME IX / CWB / API / EWI / RWMA / BSEE
Scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality." Nikola Tesla
Scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality." Nikola Tesla