WWII ship construction slugging welds

Tom's account of welders at the end of a long shift throwing stub electrodes into the groove and welding over them, with no X-ray to catch the resulting defect in armor plate. Mechanism explanation for why the Liberty-ship welds had notches.

It turns out they failed for two reasons. The steel was somewhat brittle, so it was like paper as opposed to rubber. And they had notches, and the notches were due to welding defects. The welds weren't necessarily bad — they weren't perfect, actually. Sometimes during World War II, people would take the stick electrodes — if you've ever seen a stick electrode, that's what they welded the ships together with in World War II, mostly — and after a tired long day on a big thick weldment, they would throw a bunch of these electrodes into the groove and weld over them. And no one was doing X-rays to see that they had just put a huge defect into a piece of armor plate.

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Historical precedent for the Nova Scotia case. Welders on 16-inch armor plate, bored with 600-pass joints, would throw in pieces of pipe or bundles of electrodes and bury them in the weld groove.

It was very common in World War Two when they tried to build Liberty ships and stuff. Not necessarily Liberty ships but on battleships and stuff — when you're welding 16-inch-thick armor plate it's really dull putting 600 passes into the same little section of weld. People get a little break, they might take a piece of pipe, or they may take a bunch of welding electrodes themselves, and they just throw them in the big groove, and they weld over them. No one could find it because they're buried between several inches of steel in this old armor plate. But it did weaken the whole thing. It's like making perforated steel.