Heavyyyyy!!! 40mm full metal duralumin bars with inserted threads...

 

Not sure what that stuff is ..... but I'm thinking about 7071 T6 after the winter (when the money tree grows back to life).



How does your stuff compare to the 7071 T6 ?


I was going to make the arms solid and then just drill/tap them for the threads. But that is at least 3-4 months off




Joe

 

You are crazy man, the 7000 series AlZn alloys (commonly known as ergal) are the toughest Al alloys we have on earth.
They use that stuff for spaceships.

Pros: tough as hell (yield stress 1200Mpa, for comparsion Titanium is 500Mpa!) in what concerns mechanical stress. Lighter than everything else that has the same YS.

Cons: Not so light, fragile to impacts (it behaves like a glass), doesn't like tooling very much, susceptibility to corrosion and very very expensive.


The duralumin AlCuMg alloys (2000-3000 series, YS=500Mpa) are 5 times tougher than common Al, up to 2 times tougher than steel (depending on the steel) and are widely used in aircraft industries.

Pros: Tough and ductile at the same time, excellent tooling, resistance to corrosion and very light.
Cons: Expensive, not the toughest and often what is sold as Duralumin is the common 5000 series that we can find in our cars.

The aircraft duralumin can be found (not so easily) in aircraft scrapyards, and regenerated (scrap recycled) extruded, rolled and forged shapes of every kind.

I would go for that, unless money isn't a problem for you.
Ergal is excessive, not worth, unless you want to wheel it on the moon..

 

I'm crazy because I picked the wrong 7000 series aluminum.


I meant to say heat treated 7075 .... not 7071




The 7075 is quite common in the offroad world .......



Now, please compare your stuff to the correct metal this time.

 

Ah, ok, it's basically the 2024 T4 with an additional heat treatment that raises the upper YS limit of about 50Mpa (550Mpa max), but it becomes non-weldable.
Excellent polishability and corrosion resistance, good tooling, widely used for climbing equipment, bicycles and stuff like that because of the shiny polish.
Still more expensive than the 2024 and not so easy to find as scrap.
You have those wonderful airplane scrapyards in the states where you can really get some good Avional for cheap...
worth a trip..

 

I don't know of any local or semi local airplane scrap yards .... so for me it's easier just to have a piece of solid stock machined to size.


Unless you want to suggest another composition alloy ?



Joe

 

There are many, it's only a matter of costs.

 

Spit a few out ... and I will keep my eyes open. Will keep the steel arms as "back-up" when the time comes.

 

2024 all the way.
Anything tougher than that is going to tear your mounts.

 

Unlikely.




Joe

 

Ok, here is a comparison table with the most common Al alloys that should clear this better.

 

This is the sigma-epsilon (yield-stress) diagram that shows what happens to a metal bar when it is subjected to an increasing force until it breaks.


The straight slope corresponds to the elastic region of the material. "The memory".

As the applied force (stress) increases, the poor aluminum bar is not able to hold the deformation (strain) anymore and literally collapses, letting the atomic planes start to slide and move dislocations (crystal plane edges) all around. This point gives us the Yield Strength of the material.

After the YS, the material enters the plastic (non reversible) region and immediately starts to resist to the deformation when all the dislocations have slided (strain hardening), untill it reaches the ultimate strength, it can't take it anymore, it surrenders and choses a random section for necking.... SNAP!!!

 

Now that's good stuff to see in a thread. I know we have intelligent folks on this board (sorry Fantic, you're classified neurotic). What do we need to do to get them out of the woodwork?



I'll have to compare the 2024 to 7075 and see what the difference in elasticity and strength are. Maybe in Jan or Feb (when things are quiet) I might try some alum arms.


Perhaps the engine/trans skid can be of the same material. I know I can't get back to OE weight ... but if I can control the amount & location of the excess weight, it will only improve the handling of the vehicle.


Would be a lot of work to make an all aluminum crossmember --- but there is a certain wow factor in that. Not to mention 901 people saying " It will never hold up "



Joe

 

Post some hotties pics..



and it won't sink like a battleship in the first mud hole...

Well those people should say that the next time they get on a plane and watch the wing ends flecting 12 feet in a bad turbolence... "it will never hold up"....

 

Guys, i'm having a really hard time enjoying this build thread!!!!
You two should just get married and call it a day!!...........JK!!