6082 aluminium heat treating, help?

[dusse123]

Hey everybody,

I've done a fair bit of mild steel welding but now I am making an aluminium project for the first time. I'm making a ski bike, it will be a bit like a north legion smx if anyone is interested.

I will be buying 6082 box section aluminium and it comes in a T6 condition. I know from my research that this type of aluminium will lose a lot of its strength when welded so I should get it heat treated to get it back to T6 condition.

But here is my problem, as I said earlier the metal will already be in T6 and when I weld it only a small part of the aluminium will lose its T6 temper, is it possible to heat treat to aluminium normally without changing the metal that is already in T6 condition?

Sorry if my wording is a bit hard to understand, I tried my best but if you dont understand the question please say.

Thanks for the help

Angus

[Jigantor]

Send it to a heat treatment company. They will heat treat the frame to T6.
Ji

[dusse123]

Yeah, I'm going to send it off but what I was wondering was if getting certain sections back to T6 temper will affect the rest of the metal that is already in T6 temper.
Thanks

[Jigantor]

The temper process will not damage the aluminium.
It is a process that the aluminium has already been through.
If you have designed your frame correctly you would have checked bending, shear, tensile strength and deflection. T6 makes the tensile strength much stronger than non tempered ali. And if you have designed this unit correctly you would know that temper does not help deflection, aluminiums greatest weakness a part from fatigue which is due to repeated flexing.

Ji

[Jigantor]

If the frame shape is like a push bike than it will consist of triangles where all the centroids or nodes line up. To work out the stresses involved you would employ truss analysis. This means that there is no bending moments just tension & compression acting on the members. Deflection will not be a problem in this case. That said it would be very difficult to make a frame that is a perfect truss without eccentric loading.

Ji

[dusse123]

sorry I'm not being very clear, what i'm asking is that when i get it heat treated in a furnace the entire frame will be affected and if i'm trying to get certain parts to t6 will the sections that already are t6 change to another temper?

[snowbird]

NO. Your heat treater will provide you what you want.

Some basic infos here: http://www.matweb.com/reference/aluminumtemper.aspx

Don't beleive everything you find on the internet. BUT if jiganitor suggested me to pay attention to design details when using alu alloys i would take good note of it before spending money on h.t.

good luck.

[dusse123]

Ok thanks, I'm a complete newbie when it comes to alumnium. How do you do I work out all of the things you said?

"If you have designed your frame correctly you would have checked bending, shear, tensile strength and deflection."

I've done quite a bit of research but couldnt find anything along those lines. I've talked to a fabricator who is going to teach me how to weld alu and supervise me doing it, he said 2mm thick would be enough, I'm using 50mm x 50mm 6082 tubing.

Any help would be appreciated!

[Jigantor]

To understand these concepts you would have to do a Uni degree in engineering or work with someone that crunches calcs every day for a few years. That said the best thing to do first is to draw your design with all the members. Work out dimensions and then estimate what you believe to be all the loads that will be applied to the frame with their respective angles.

Ji

[dusse123]

To understand these concepts you would have to do a Uni degree in engineering or work with someone that crunches calcs every day for a few years. That said the best thing to do first is to draw your design with all the members. Work out dimensions and then estimate what you believe to be all the loads that will be applied to the frame with their respective angles.

Ji

Or I could just over build it to remove any risks? he says hopefully...