S-N Curve, Stainless, Applcable to Various Weld Details

[mousemat]

Hi all,

I'm wondering if anyone could point me to a standard/code which would include S-N curves for various weld details using stainless steels?

I need to analyse the fatigue life of a fairly simple thin wall RHS structure that is constructed from a stainless steel of my choice.

Thanks

 

[EdStainless]

The way that this is usually handled is that you look at SN curves for notched samples and see how sensitive that alloy is to such stress concentrations.
Then you look at your weld methods (and required NDT) and decide if you will be generating greater imperfection that the notches that you referenced.
Of course in most designs the welds are in lower stress areas and are not the limiting factors in the structures strength or fatigue life.

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P.E. Metallurgy, Plymouth Tube

 

[metengr]

http://www.diva-portal.org/smash/get/diva2:7597/FULLTEXT01.pdf

 

[mousemat]

Thanks for the replies thus far. To clarify my situation in more detail:

I will be analysing the fatigue life of the structure using the nominal stress approach. The structure is comprised of S/S thin wall hollow sections connected using welds.

My problem is that I don't know which standard has a list of weld details and associated S-N curves that are applicable to stainless steel.

From the research I have done it appears there are no standards with this information and that for fatigue analysis purposes the S/S member welded connection is to be considered as if it was instead C-Mn. For example DNV RP C203 states:

"For Duplex and for Super Duplex steel one may use the same
classification as for C-Mn steels.
Also for austenitic steel one may use the same classification as
for C-Mn steels."

All well and good but unless I'm missing something the weld detail list and associated S-N curves published in DNV RP C203 are not applicable to C-Mn weld details.

Thanks