6005-T5 wing spar

[jeanch12]

Hello,
Does anybody have knowledge or experience about using aluminum alloy 6005-T5 for a small aircraft extruded wing spar in direct replacement of 6061-T6 ?
Would you recommand it ?
I cannot find anything on the subject and are completely ignorant....
Thanks for any input !

 

[kenvlach]

Per ASTM B221, 6005-T5 has the same YS & elongation requirements as 6061-T6, but beware 6005A-T5 (about 11% worse). However, 6005-T5 seems to lack fracture toughness test data...

Rather illegal to use non-listed material in aircraft; aircraft using non-listed materials cannot be certified as airworthy. Canadian regulations are likely similar to US.
The only 6000-series alloys in MMPDS-01 Metallic Materials Properties Development and Standardization Handbook (January 2003) [formerly MIL-HDBK-5J] are 6013, 6161 and 6151 (and 6151 use has been restricted primarily to die forgings).
Note: There is a newer, (legal) MMPDS-02 but it co$t$.

Try 6013:
"3.6.1 6013 ALLOY
3.6.1.0 Comments and Properties — 6013 is a Mg-Si-Cu-Mn alloy which is weldable. This alloy has 25 percent higher strength in the T6 temper than 6061-T6. It has improved toughness, fatigue strength, and stretch forming characteristics compared to 6061 with equivalent stress corrosion characteristics."
from MMPDS-01 Metallic Materials Properties Development and Standardization (formerly MIL-HDBK-5J)

 

[jeanch12]

Thanks for this answer kenvlash
I am worried buy the fracture toughtness weakness, furthermore by the absence of information.

Is 6013 used in extrusions ? It seems more used for machined parts from block

 

[kenvlach]

6013 is approved for aerospace and has a lot more materials data available than does 6005. See
MIL-HDBK-5J METALLIC MATERIALS AND ELEMENTS FOR AEROSPACE VEHICLE STRUCTURES (Jan 2003)

http://assist.daps.dla.mil/quicksearch/basic_profile.cfm?ident_number=53876

Note 1: This is a 79 MB download. I believe that someone has posted the separate chapters (e.g., Aluminum Alloys) for downloading, but don't have the link.

Note: the current AEROSPACE Materials specs. are now DOT/FAA/AR-MMPDS, “Metallic Materials Properties Development and Standardization (MMPDS),” but costs about $500.

 

[rb1957]

if you're worried about fracture, why not replace the 6005 with 2024 (unless of course you're welding the spar together) ?

 

[SAITAETGrad]

Why not use 6061-T6? It is readily available and inexpensive. What is driving the change to 6005? Note that the 6061-T6 has excellent fatigue properties. This is another important factor for your wing spar replacement modification.

Perhaps this question is from a homebuilder (experimental aircraft)? I'm assuming you are, as 6061-T6 is a popular material amongst experimental aircraft designers and probably not often used for wing spars outside of that niche. Please note that not all 6061-T6 bars or extrusions are created equal. 6061 describes the chemical composition and T6 the aged (heat treat) condition method. A secondary specification such as SAE-QQ-A-200/5 more specifically defines the material condition to something useable for aircraft engineering with published engineering data values found in publications like MMPDS-01/-02. This is not to say that commercial material at your local metal shop is inferior. You just need to find what specifications the materials meet and compare with the design material.

If you have any doubt on your competence on this issue, please ensure you fully understand the changes you are making before moving forward. Do not hesitate to ask for help.

 

[jeanch12]

Why not use 6061-T6 is exactly the question I am asking myself...
Yes I have an amateur wing design project and found a local company offering a kit for a similar wing (with this 6005-T5 spar). Because of the time economy, I played with the idea. But I had no clue of this 6005-T5 so asked arround and on the web. Now I know that I am not the only one and, since the extensive study & testing that would be good practice in my opinion is behind my capabilities and skills, I know I wont go this route.
Thanks to all that answered this thread ! That was very valuable and I finally made a decision

 

[kenvlach]

Correct decision.
An easy way to compare 2 alloys is to pull up their MatWeb pages side-by-side:

http://www.matweb.com/search/SpecificMaterial.asp?bassnum=MA6005T5

http://www.matweb.com/search/SpecificMaterial.asp?bassnum=MA6061T6

Thus readily seen that 6061-T6 has higher YS & elongation, plus toughness & fatigue data lacking for 6005-T5.