50,000-ton Wyman-Gordon forging press structural crack

Tom visited Wyman-Gordon (North Grafton, MA; later acquired by Krupp) in the early 1980s to investigate a crack in a forged I-beam at the base of the Air-Force-built 50,000-ton press. Six 300-ton I-beams at top and bottom; one had cracked at a weld over thirty years of service. Replacement estimated at two billion dollars in 1983.

I've been to it once back in the early '80s when it had a crack. The forging floor is basically a dirt floor, and you have these columns going up about five or six stories. They're about four feet in diameter — probably five or six — and there are six of them. You have a big hydraulic hammer up here that's going to come down. The base underneath goes down for six stories. I had to go down in an elevator to see one of the beams at the bottom. They had a series at the top, and at the bottom they had a series of I-beams which had a cross-section that looked something like this, and each one was forged. The top surface was machined within ten-thousandths of an inch because it had to be the machine base. The web thickness was about nine inches if I remember, and the whole thing was like six feet tall. It weighed 300 tons for each one of these beams. There were six of them across the base and six across the top. One had developed a crack at a weld over the thirty-year history of this thing being a forging press. The estimated cost to replace the whole unit was two billion dollars in 1983.

One of two free-world 50,000-ton presses (the other at Alcoa Cleveland). Six I-beams ten feet tall, ten-inch web, fifteen-inch flanges, holding the press structure six stories below grade. 10-foot crack in one beam, $2 billion replacement cost in 1980 dollars. Tom consulted; recommended rigging the beam up and out for stress relief in a built furnace rather than in-place. Critical flaw size 10 inches — fatigue crack initiating at the toe of a fillet weld on a 50-pound rigging block someone had left attached. Punchline: "We didn't know how to weld 10-inch-thick material without stress relieving it. We lost that technology when a lot of people died of old age."

This is one where obviously the nut wasn't tight — it was peening itself apart. And another one with some really big bolts — this was a 50,000-ton forging press. There are only like half a dozen of these in the world. The posts are basically four bolts, four big bolts about a meter across. Stress concentration, there's the fatigue crack, there's the final fracture. They changed the steel and they thought they were going to a higher strength steel and everything would be wonderful. The fatigue crack is this big, there's the final fracture area. Yeah, it was higher strength, but it still broke through fracture mechanics. We won't get into the fracture mechanics right now.