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I made a pallet lift table out of 1/4" SS304 and now have about 5x the deflection that beam calculations predict. I noticed that the machine was shipped supporting a 500lb pallet. I thinking a few things: 1. Either shock loading from the 500lb pallet when the truck was going over bumps exceeding yield. 2. Creep from the pallet being supported for about a week now. Computer stress was about 6000psi, so pretty far from yield.

The table had two edges bent up on a press brake. One end of the table needs to be open to roll pallet lifts onto the table. I'm thing of going from 1/4" SS304 with edges bent on a press brake to welded 3/8" T1 A514. The yield of T1 is about 90kpsi, about 2x more than SS304.

Does anyone know the creep / cold flow SS304 vs A514/T1? Is there calculations to compute? I'm also open to comments/suggestions.

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    $\begingroup$ IMO, forget about creep and cold flow until you have correctly included the flexibility of the parts which your beam analysis assumed were rigid. Without a drawing, we can only guess what your structure is like, so it's impossible to be more specific. $\endgroup$ – alephzero Oct 27 '18 at 18:43
  • $\begingroup$ Agree with alephzero. Your connections probably aren't as fixed as you modelled them to be. $\endgroup$ – Wasabi Oct 27 '18 at 18:53
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Per Blacksmith37, those alloys do not creep at all at room temperature and so neither do they cold flow under that low a stress level. Suggest you check your original stress calculations.

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  • $\begingroup$ I suggest removing the phrase "For all practical intents". T 1 will begin to "relax" at about 600F with very high stresses, total strain of less than 0.i % . ( A problem for high temperature bolting .) $\endgroup$ – blacksmith37 Oct 28 '18 at 21:38
  • $\begingroup$ The lowest temperature I found creep data for 304 was 800 F. And it was the same range of values at the hot tensile tests at the same temperature, That is, you must have yield level stresses to cause creep at 800 F. $\endgroup$ – blacksmith37 Oct 29 '18 at 0:12

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