Mechanical Fatigue of A321 SS

[DRW75]

Hey folks,

Just a question regarding the properties of A321 stainless. I'm a structural engineer by trade, and am not too familiar with more exotic material properties and would appreciate a little direction.

I've been doing some looking online for A321 properties, and have found some consensus, but would appreciate a nod from the folks that know - I hate taking stuff from online at face value.

It seems to say online that the fatigue endurance limit for A321 is approximately 35% of the tensile strength. For my application, the operating temperature is about 550 degrees Celsius, and service time is about 100,000 hours.

So the properties that I am currently working with are:
yield strength = 150-190 MPa
Ult Tensile Str = 360-390 MPa
Endurance Limit = 0.35*360 = 125 MPa <- this number seems kind of high?

I know it seems to be tough to nail down some good figures, but I am selecting design values which are very conservative with respect to the numbers listed above, and would just like to get a nice warm fuzzy feeling that the final numbers that I've selected have an ample buffer of safety/uncertainty.

thanks

DRW

 

[EdStainless]

Are you looking for fatigue limit at 550C?
Then you need strengths at 550C to work with.

Are you really looking for fatigue, or is creap and stress rupture the more important.

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[DRW75]

I checked creep & stress rupture just to be complete (thats why I had included 100000h service time), but these stress values are much higher than the operating conditions.

My primary concern was fatigue due to fairly low loading (about 10MPa stress), but relatively high cycles (1-2,000,000,000 estimated cycles).