Heat Treatment

[Luckies]

I would like to ask for a brief procedure for heat treating 2024 t3 aluminum to t0 condition. Will it return to its original state (t3) for a specific time? Its been a practice here in our company to heat treat it to 40min. then bend it (0.083 thick). They say that it will return to its t3 state after sometime (i forgot the specifics). Im a bit concerned about the grain arrangement and they dont have proper documentation to support it at that time so I dont know if i should adapt to their practice or not.

Thanks

 

[berkshire]

Luckies (Aerospace)

Are you sure you want the material back to t0. This usually involves heating to 775 degrees fahrenheit and cooling slowly. This is done to remove the effects of heat treating.

The W or AQ temper is used for softening a part to enable it to be formed, generally by heating the part to around 920 degrees F then quenching the part (The time in the heat treatment varies from 10mins to an hour depending on the thickness of the part.) this is an unstable condition and the part will naturally harden to the t4 condition in a short time, unless it is refrigerated to about 0 degrees F
B.E.

 

[Luckies]

From the info u provided i say that they just softening it.
they putting it in the oven for about 40min 923degF, quench it (regardless of the thickness as long its hard to form).

Im new to this kind of idea bcoz im my previous company, we fabricate parts with thick materials in t0 condition and send them to a facility with the license to heat treat.

So how about the grains? Is this critical?

 

[berkshire]

Luckies (Aerospace)
I am a little unclear about your question about grain arrangement, Are you talking about the grain direction of the material the part was cut from, or are you talking about grain growth from holding the part at heat for too long?
If your part is freshly quenched you should not have a problem forming it since the AQ temper is very close to the O condition for a short while and even bending along the grain direction should be possible provided you do not use too tight a bend radius.
You may find more information on this in DOT/FAA/ar-mmpds-01 the old Mil-Hdbk-5 However unless your company already has this you may have to pay for it now. I think mmpds is now up to revision 03.
B.E.

 

[Luckies]

Sorry the term i gave u was wrong, what i mean was grain boundary. And I was asking a wrong question. I just learned that is not about soaking but the speed of the quenching.

"To obtain optimum physical properties of aluminum alloys, rapid quenching is required. The recommended time interval between removal from the heat and immersion is 10 seconds or less. Allowing the metal to cool before quenching promotes intergranular corrosion and slightly affects the hardness. This is caused by re-precipitation along grain boundaries and in certain slip planes." -tpub.com

Thanks berk for making my questions clear and answering them as well.. til next time

 

[berkshire]

Luckies (Aerospace)
I am presuming that you are using a drop bottom oven over a quench tank. If you are you should not have problems with quench time.
B.E.