Fatigue Law Material Constants - Inconel X-750?

[mkenwort]

Per Ashby and Jones, the crack growth rate is described by:

da/dN = A(deltaK)^m

and goes on to say that A and m are material constants. Has anyone turned up A, m data on any web resources for Inconel alloys? I've seen a few journal article abstracts that make reference to them, but nothing easily accessible. Worse comes to worse I'll just write a purchase req, but it could take days for me to get the answer.

Only numbers I've found are for cast iron: m = 4, A = 4.3 * 10^-8 m (MNm^-3/2)^-4; these are found in a rather cool case study of the Stretham Engine in the Ashby and Jones book (Engineering Materials I, 2nd edition)

MIL-HDBK-5 turns up some interesting graphs for Inconel 718 (6-74 through 6-76), but no specific values for m or A.

Thanks in advance.

 

[Carburize]

There is a section in ASM Handbook Volume 19 "Fatigue and Fracture" on Fatigue Crack Propagation in nickel base alloys - I don't see any numbers for the constant or exponent in the fatigue crack equation (which is actually known as the Paris equation) but if you dig into some of the reference material quoted in that section you might find what you are looking for.

 

[Carburize]

I just did a Google search using " exponents in the Paris fatigue crack propagation law for Inconel 718" and hit two or three papers which you might find useful.