7500-ton forging press failure

1949-vintage 7,500-ton forging press used for forging aluminum truck wheels; cracked through a 14-inch section of cast steel cap (~60-ton, ~10 inches thick). Repair welded with 300–400 stick-electrode passes. First repair cracked before reinstallation; second repair cracked on first forging stroke; both failures attributed to hydrogen buried under successive passes without adequate post-heat. Tom uses it to teach why diffusivity (10⁻⁶ cm²/s) makes thick-section hydrogen extraction nearly impossible without staged post-heating.

This was part of a forging press, built originally in 1949, that developed a crack. It was about a 10-inch — big cast steel, this is cast steel along here, this is the weld zone. They had a crack. This was a 7,500 ton forging press. They were forging aluminum wheels for trucks. And you don't have a lot of spare 7,500 ton presses. This was about a 60-ton cap to the forging press — the top of the press — about 10 inches thick. The crack ran through a section about 14 inches in the direction the crack ran. So they gouged it out.

Cited as the kind of heavy machinery that falls under AWS D14 (welded joints in machinery equipment) rather than D1 (structural) or the ASME boiler and pressure vessel code.

The American Welding Society knows they can make a lot of money by selling codes, and so they have part of the structural welding code, the D14 series. The big structural welding code we've been talking about is D1 for steel. D1.1 is steel, D1.2 is aluminum — we'll talk about that later. D14 is specific industries: welded joints in machinery equipment, welding of presses and press components. When I talked about that great big 7,500-ton forging press, here's the code that applies to that. It's not very thick, partly because it calls out the ASME Boiler and Pressure Vessel Code, which is this thing.