I too need this data but haven't had the time to track it down yet. I found a reference in a source but don't know how good it is.
J.F.Janowak, A.Alagarsamy, and D. Venugoplalan, "Fatigue Strength of Commercial Ductile Irons.", Transactions, American Foundrymen's Society, Vol 98, 1990, Paper #90-123.
I hope this helps. If you do find a source I would appriciate you letting me know what it is.
ASM Metals Handbook, Ninth Edition, Volume 1 contains text and graphs on fatigue life and fatigue limit, beginning on page 21, with additional info beginning on page 43 and then on page 665. The handbook is available in most reference libraries.
I don't know what is in the 9th edition, but the tenth edition has several S-N curves on page 39 for specific grades. None of which are 60-40-18 or 65-45-12. On page 47 in has a band for S-N data but the band is about 10ksi wide. (i.e. typical values). From this a person might make a reasonable "guess" but that is probably not good enough for an optimized design or a FAA requirement.
