I tried to TIG weld a 1/2" pipe nipple, to a 16 gauge sheetmetal piece, so that the pipe nipple is perpendicular to the sheet metal.
The objective was to make a little stand on which I would mount a VFD.
I used about 100 amps of current, DCEN, and ER70 filler rod.
The temperature in the garage was about 40F.
The result was a decent looking TIG weld, nothing to brag about, but passable.
However, as soon as I stopped welding, the weld zone began to cool and started making little popping noises. After a minute or two, I whacked the 16 ga sheet to straghten it, as it was warped a little.
After just one or two whacks, the sheetmetal piece FELL OFF, basically cleanly, with the entire weld remaining attached to the pipe nipple.
I was completely shocked. After looking at the failure area, I had an impression that some cracks developed UNDER the weld and a part of the sheetmetal stuck to the weld, so the weld, sort of, tore off a part of this sheetmetal piece, as if it cracked in the middle.
I feel kind of fortunate that this was never meant to be a structural piece, but I get some jitters just thinking about what would happen if it was.
Would anyone have any clue as to what it could have been.
i