S-N of AW 6082 T4

[malchev]

Hallo,

I cannot find fatigue material parameters (S-N Curve) of the EN AW 6082 T4 (DIN AlMgSi1 F21) Aluminium Alloy.

If anyone knows sth. about please help.

D. Malchev

 

[TVP]

I doubt that you will find any information for this alloy in the T4 temper. It is supposed to be artificially aged to the T6 temper for optimum properties.

 

[malchev]

Thanks TVP,

what You say is right. I'm looking for this data since a week without any success. Do You think that T6 will have much different properties than T4?

Regards
Delyan Malchev

 

[israelkk]

Why not build the S-N curve yourself as it is done in any machine design book using 0.9 of the yield strength at 1000 cycles and the 0.4-0.5 yield strength at the 10,000,000 cycles on a half log graph?

 

[malchev]

Yes, ok, israelkk,

I will do a fatigue calculation after that, that means that any approximation in the S-N curve will affect life of the component.

I know how it is done, but prefer not to do this.
Thank you.
Delyan Malchev

 

[israelkk]

I see that you are in the aerospace business. I do not recall that AL 6082 is listed in MIL-HDBK-5. Are you designing it for aerospace use?

 

[malchev]

Yes, the material is in our laboratory. I have to calculate the expected life of an exsisiting structure.

 

[TVP]

malchev,

Yes, the fatigue life of alloy 6082 will be significantly different between the T4 and T6 tempers. If you do not perform testing on the actual material you have, then israelkk's suggestion is the best way to estimate the properties. Why do you want to use the T4 temper instead of T6?

 

[malchev]

TVP,

I cannot choose what material to use; it is a standard material, available in the laboratory. If I don't find anything about 6082T4, I will have to approximate.

 

[israelkk]

The whole fatigue calculation method is not so accurate. In the aerospace field ususally the spec requires a factor of safety of 4 to 10. Therefore, the approximated graph is almost as good as any graph you will find. All this without taking into account the quality of the alloy, the exact surface finish, exact stress state etc. which will add to the uncertainty of the fatigue analysis.

 

[malchev]

israelkk,

you are right, I know I can always approximate the S-N curve and that's what I am going to do.

Thank you for your help.

 

[jamest1]

Hi Israelkk

I think I am having a similar problem with a die cast aluminum LM6 part.

Could you suggest how I could build an S-N curve as shown in a book, or suggest a book from which I could use the equation?

Thanks