welded inconel 625 sheet fatigue/static strength
welded inconel 625 sheet fatigue/static strength
(OP)
Long time lurker, first time poster here. Hoping someone can shed some light on my problem...
I have (2) thin 0.063" thick inconel 625 sheet materials welded together using AMS5837 filler material with a complete penetration corner joint. The weld will be thermally loaded as well as put into low magnitude bending.
I am looking for a way to analyze this joint for both fatigue and static strength. I am having extreme difficulty finding published data on the allowable static stresses (or design strengths) in inconel welds. I am also having difficulty finding any kind of s-N curves for welded 625 inconel sheet. I am more worried about the fatigue analysis. What would you recommend i do? Essentially i need the data found in the AWS D1.1_ Structural Welding Code, only for inconel instead of steeel.
I have (2) thin 0.063" thick inconel 625 sheet materials welded together using AMS5837 filler material with a complete penetration corner joint. The weld will be thermally loaded as well as put into low magnitude bending.
I am looking for a way to analyze this joint for both fatigue and static strength. I am having extreme difficulty finding published data on the allowable static stresses (or design strengths) in inconel welds. I am also having difficulty finding any kind of s-N curves for welded 625 inconel sheet. I am more worried about the fatigue analysis. What would you recommend i do? Essentially i need the data found in the AWS D1.1_ Structural Welding Code, only for inconel instead of steeel.





RE: welded inconel 625 sheet fatigue/static strength
http://www.alloywire.com/inconel_alloy_625.html
RE: welded inconel 625 sheet fatigue/static strength
RE: welded inconel 625 sheet fatigue/static strength
htt
http://www.ascgenoa.com/main/newsletter/9/[2]6-07_AIAA_2007_2381-metal-Fatigue.pdf
Hope they help!
RE: welded inconel 625 sheet fatigue/static strength
RE: welded inconel 625 sheet fatigue/static strength
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Plymouth Tube
RE: welded inconel 625 sheet fatigue/static strength
RE: welded inconel 625 sheet fatigue/static strength
RE: welded inconel 625 sheet fatigue/static strength
"The properties given in this bulletin, results of extensive
testing, are typical of the alloy but should NOT be
used for specification purposes."
RE: welded inconel 625 sheet fatigue/static strength
TorsionalStress.... has done an excellent job of pointed you in the right direction and given you considerable info., in considerable detail. Undoubtedly, you could find some more basic material properties info. from other material suppliers; and possibly some S-N curves for polished virgin material. Check with your filler metal supplier for info. on that exact material, and the welds produced by it. Because that info. is just as important in addressing your problem. Otherwise, the only thing he hasn't done is run the tests, for you, to produce the S-N curves for your exact detail, loading conditions, welding procedures, etc., all of which you have not done a very good job of describing in enough detail.
You can infer all kinds of things (maybe good approximations) from existing S-N curves for various materials, and similar details or detail dimensions, etc., we do it quite often, but these are just educated engineering judgements unless you test your own detail and conditions; even down to such details as the orientation of the rolling grain in your sheet stock. You have to make a determination of the number of cycles you expect to see, then run a bunch of samples to some higher number of cycles, or to failure, so you start developing the S-N curve for your condition. I suspect you would be very lucky, indeed, to find curves someone else had developed which fit your conditions exactly. Also, we use average, actually minimum, mechanical properties for materials all the time in design.
RE: welded inconel 625 sheet fatigue/static strength
I guess I was incorrectly thinking that there were established fatigue s-n curves for inconel just as there are for Steel in the AWS D1.1 Structural Welding Document. From your reply it appears that this is an incorrect assumption.
thank you for your time. I apologize for the lack of clarity in my problem statement.
RE: welded inconel 625 sheet fatigue/static strength
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Plymouth Tube
RE: welded inconel 625 sheet fatigue/static strength
RE: welded inconel 625 sheet fatigue/static strength
Torsional stress, weld backing may be possible on this joint, but could not be permanent. Does weld backing provide any benefits to the material properites of the welds? What would be the benefit of the backing?
RE: welded inconel 625 sheet fatigue/static strength
RE: welded inconel 625 sheet fatigue/static strength
RE: welded inconel 625 sheet fatigue/static strength
Here is a cross section of the weld
http://postimage.org/image/2afkz24h0/
I believe i may have found a solution to my problem of fatigue analysis. Norton's Machine Design has a very good section on estimating fatigue strengths of materials not covered by testing or published data (see pages 324-337). The only thing lacking in the analysis is a formula for estimating the starting theoretical fatigue strength of inconel welds. Steel is shown as having Se=.5Sut, and iron/aluminum/copper=.4Sut. If I am conservative and just assume 0.4Sut for the theoretical starting fatigue strength of inconel, use Sut for the inconel filler weld material (and not the parent material), use "as forged" for the surface factor, and then factor in all of the welding correction factors listed, I think I should have a good conservative approximation (that can be documented and referenced back to published methods). Does anyone see any flaws in this approach?
Interesting that I found various sources saying that inconel DID and DID NOT have an endurance limit :
those that did: (http://
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those that did not: (see Machine design, Norton, pg 312).