While doing some training, WPS development, PQR, and certification test preparation, I ran into a rash of fillet weld break test failures. We are using 1/2" A-36 plate, GMAW-S, .035, 90-10, D1.1 (not pre-qualified). This customer has not done any kind of PQR testing before. The test welds show very good penetration on the macro etch, but when pressed, the root fails regardless of penetration level. The fracture has a brittle surface profile look, with little (<.010") round porosity looking inclusions. When the part breaks it snaps from the root and does not tear any parent material with the weld. I asked for the material certs and the wire certs and found nothing out of the ordinary. I'm puzzled about the look of the failures, and the lack of parent material pulling. We have qualified FCAW, GMAW globular, GTAW, and never had failures like this. Anybody experienced this before?
Mark
Are they actually inclusions-i.e. porosity with something in em?
What wire are you using? S-2?
Triple deox S-2 will sometimes leave pepper looking deposits Ti, Zr, and Al) in clean weld/base metal.
Just a thought, although I would suspect they would have shown up on the etch. Unless they were really small and only visible with fracture.
Still, I've never known this phenomena to cause fracture.
Half inch is pretty thick for short circuit... but can be done :)
How about mill scale? Short circuit GMAW hates mill scale.
If you are using ER70S-3 a change to -6 might float away some oxides that could cause junk at the root.
Yes, I did ask them to get S-6 wire as the next course of action. We are currently using S-3, and I thought it might be adding to the problem.
At first they were welding over the scale, but now all test plates are ground/ sanded to remove any scale. It did not show any improvment one way or the other.
Yes 1/2 takes a lot for GMAW-S, but we are trying to get 5/16 single pass for qualification testing. I also suggested .045 in leu of the .035 they want to use.
Thanks for the input!
Mark
Good point Lawrence. If he is using the more viscous S-2 and S-3 on 1/2" plate there could be trapped oxides.
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