Bay Bridge California corrosion-induced hydrogen cracking

Don Sadoway forwarded Tom a link to this case. Tom uses it to illustrate that hydrogen embrittlement of steel doesn't require a welding arc — corrosion in seawater plus stress is enough.

I meant to bring — Don Sadoway, a faculty member of this department, sent me a link to a problem they're having on the Oakland Bay Bridge. They have some big steel tie rods, and they're corroding and breaking, and they're holding this bridge up. It's a multi-billion-dollar bridge. It's hydrogen cracking, because it doesn't show up right away — it takes a few days to show up. It's due to corrosion. Another way to get hydrogen into the steel is not just a welding arc plasma — it can be by a corrosion process. You can take a bolt that has no welds, stick it in seawater, put a stress on it, and the bolt will crack in a couple weeks because of hydrogen cracking. So it's not just welding, it's lots of other things. One of steel's Achilles' heels is hydrogen embrittlement. Other materials have hydrogen embrittlement too.

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The 46-inch-diameter steel tie rods cracked within weeks after corrosion-generated hydrogen diffused into the steel. Used to extend the hydrogen-cracking framework from welds to corrosion.

These problems show up all the time. The Bay Bridge in California — it's coming from corrosion. They have big 46-inch-diameter steel tie rods, and they started corroding. The corrosion process creates hydrogen that diffuses into the steel — not as much as in welding — and they said, oh, they cracked within a couple of weeks. Well, that's hydrogen. The hydrogen will usually diffuse out within a few days. For federal highway work, you don't do your inspection for cracks until 72 hours later, because the cracks usually form in the first few days. The US Navy and some shipyards wait seven days. Make sure the cracks have formed if they're going to form. What good does it do to inspect if the cracks haven't formed yet and they form after you inspected?