About heat treatment of Al 6351

[tarun garg]

Hi!

We are planning to make the uprights of our car out of Al 6351T6.

We have decided that we would get aluminium billets from aluminium manufacturers that would consist of composition of Al 6351. Then the billets would be melted and casted into the desired shapes. Then we plan to heat treat the aluminium, the heat treatment being the T6 process.

We hope to conduct physical tests on the final material but hope that the properties of the final material are close to the ones mentioned on the internet.

I would really appreciate if anyone could share their experience in similar quests! Or any comments.

Thanks
team.fateh@gmail.com

[BenB]

I've never used 6351, but I do know that some Aluminums are more prone to fatigue fracture than the aerospace aluminums (mainly 6061 and 7075). Not saying 6351 has a problem, but be aware of that.

Unfortunatly it is normally hard to find fatigue testing data for most materials. They are easier to find for more commonly used ones though.

[Drew Price]

Tarun,

I'm not even going to touch this one, you need to speak with someone experienced and knowledgeable about casting structural aluminum.

Aluminum alloys designed for casting are not the same as those designed to be furnished as billets or even for forgings. Castable AL alloys are usually a 3-character designation (like A380) rather than a 4-character designation like your 6351, you need to see if it's even possible to cast it, and if it's compatible with the process you want to use, whether it's invenstment casting, sand cast, whatever. Some castable alloys are also not heat treatable, some are, but whether the processes or designations are the same I couldn't say.

I would bet that you cannot count on the data sheet for 6351-T6 remaining accurate after you melt it down, especially if it was furnished straightened or rolled to finished shape after heat treat, probably a T651 or T6511 designation.

Actually, I would say that you absolutely can't count on it, but you could case a small ingot in the same process you will try to make your uprights from and have a properties test done to at least find yield and ultimate strength, elongation at break, etc. A fatigue test would be even better, but I'm pretty sure I couldn't even arrange a legit fatigue test, it's very possible you won't be able to either.

Castable alloys I believe differ in their flow and viscosity properties when molten, just melting down a billet might make something that will not fill your mold properly, and may have very uneven grain formation, things like that.

Also, this is not really a place where you are likely to find good acvice on this subject, it's too specialized. Try a machinists or foundryman's forum, or something like that. There are only a few teams here who successfully cast structural parts, and they have put an aweful lot of research into it, not something you can just jump into.

Best,
Drew