I need to find out the minimum allowable working temperture of 316 and 17-4 annealled and at condition H900. I have looked in ASME B&PV Code with little success. Can anyone tell me a resourse to look up.
"The impact strength of 17-4PH, especially large size bar in the H900 and H925 conditions, may be very
low at subzero temperatures; consequently, the use of 17-4PH for critical applications at low temperatures
should be avoided. For non-impact applications, such as valve seats, parts in the H925 condition have
performed satisfactorily down to -320F. The H1100 and H1150 conditions have improved impact strength
so that parts made from small diameter bar can be used down to -100EF with low risk. For critical low
temperature applications, a similar alloy, 15-5PH (consumable electrode vacuum melted), should be used
instead of 17-4PH because of its superior impact strength at low temperature."
For solution-annealed 316 SS, ASME Boiler and Pressure Vessel Code allows use up to -320 deg F. IF the minimum design metal temperature is colder than -320 deg F, impact testing and welding processes are limited for welded components.
The other thing to remember about the PH grades is that, in general, they are very notch sensitive.
Even if I was looking at 15-5 or 17-7 I would want the material in the overaged condition unless it was being strongly compressivly loaded.
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Corrosion never sleeps, but it can be managed.