Aluminium 2018 alloy question

[Victor Duarte]

Hello,
i have a question about the 2018 (NOT 2014) alu alloy :
it's elesticity modulus is far better than other alu alloys, the problem is that it's a copper- alu alloy that may have some corrosion problems.

does anyone have experimented it ? dos anyone have any valuable info about if it's possible to use it ? The use i plan to do is a flexible plate not submitted to any traction, only flexion (about 2000 N).

Thanks in advance for any info.

[Not Yet]

All Aluminum alloys that start with 2xxx have as the primiary alloying ingeredient Copper. 3xxx is Manganese, 4xxxx is Silicon, 5xxx is Magnesium, 6xxx is Magnesium & Silicon, 7xxx is Zink.
So 6061 is Aluminum & Magnesium & Silicon.

[Victor Duarte]

Thanks david ,
do you know more on its usage ?
it seems stronger than 2014 but i don't see thos alloy used commonly..why ?
thank you

[Jazzenjohn]

I saw a single refrence to it being used as wrought aluminum. I would expect that it would be poor welding as it has a similar amount of copper as 2024. 2024 is much more common.

[Victor Duarte]

that's right John,
i've read a couple of articles about alloys but no particular mention of this one.
excepted it's poor weldability and a poor corrosion resistance and eventually eletrolythical problems when assembled with others.

just to compare.-------: 2018------ 2014 --- 6061 ------ steel
elast modulus (N/mm2)-: 74,000 --- 73,000 -- 69,000 --- 210,000
traction limit ----------: 420.5 ---- 165.4 ---- 124 ------ 723.8
elast limit -------------: 317.1 ---- 96.5 ----- 55.1 ----- 620.4

Thanks

[Doug Riley]

Victor: 2018-T6 (note that the "T6" heat-treatment is very important with all of these alloys) has better mechanical properties than 6061-T6, but slightly poorer than 2024-T3 and significantly poorer than 7075-T6. The latter two are the "high-strength" alloys often used in critical components -- at least here in the U.S. With 2024-T3 so common, I wouldn't bother with the 2018. If you can't get 2024, 2018 could be a reasonable substitute, as long as you re-checked any load calculations for critical items.

I'd agree that this alloy may have poor corrosion resistance, like 2024. However, it has a 2% nickel content, which 2024 lacks. I don't know if that will make a difference with regard to corrosion.

[Victor Duarte]

Hi Doug,
very precise , like always. 2024 looks more reasonnable.
yes i fear a little corrosion problems as i designed a hub made of a central plate of 6061 for the flexion and 2 external plates to hold the blades (see joined pic, the top view), this pile is a perfect cell... damn, actually i investigate how to make it of fiberglass S (color pic), 4 times stronger 3 times lighter... maybe it's worth loosing one or 2 prototypes..

Thank you again Doug.