looks like he is not staying in the start postion long enough to actually melt into the metal. just starting and running with it so your first 1/4" or so probally has very little penatration.
I would let that go, it looks to me like the stop is built up higher then the rest of the weld so having a little depression in that area is still more metal than in the middle of the weld, as for the starts, I think i would dye-pen to see if any IF showed up and let the dye-pen make my decision for me.
Tom,
I just can't really figure out what you don't like about those welds.
If you start in the middle and end in the middle of a fillet joint with aluminum (intermittant) that's what it looks like.
Causing eventual cracks???? Don't mean to take you to the wood shed here :) Cracks are there or they are not.. The weld is compliant visually according to the acceptance criteria of D1.2 or it's not.
If you want to see full pen at the starts and stops you will most likely have some craters.. The operator took extra effort to fill the crater as he tailed off the arc, that much is obvious.
If you are really conserned I would section and etch the fillets about .125 from the starts and stops and look for fusion at the root....
Maybe I'm getting soft in my old age...... (although Al and Joe Kane don't seem to be soft in theirs >snicker< )
Actually, it is indeed a CIB to get that start 100% blended to the corner, I don't care what the process is. "By the book," you have acceptable welds there. That pocket under the start is very difficult to avoid with any aluminum; you can preheat and leave your arc on that start as long as it takes, but even the most skilled welders will likely make a molten mess of that joint before they get the "perfectly" blended start.
That was Jekyll. Here's Hyde:
I have seen starts like that develop cracks in both 5052 and 6061, with 5356 and 4043 fillers. Because the end of the weld is joined only to the outer legs of the welded section, any movement in the part can stress that part of the weld to failure. I'll bet Tommy could have some good input here, since he welds on airplanes, where this weld would likely be rejected. But for D1.2, it should be satisfactory In My Opinion. :)