Aluminum 6061 2

[davidlight]

I took some 0.050-inch 6061-T6 sheet metal and annealed it. My intent was to bring it back to the T0 temper. I programmed the oven to go to 775F, hold temp for 1.5 hours, then reduce temp at -50F per hour until 500F is reached, with a hold time of zero. So the oven turned off after that, and the part slowly air cooled. I had some hardness tests done on the specimens, and they were so soft that they were below the lowest numbers on the charts. I have not found any treatment schedules to bring it from T0 to T6, can I just use the same treatment schedule to bring T4 to T6?

 

[jsokal]

Hi,
Aluminum T0 is annealed, T4 is solution treated and naturally aged (at room temperature), and T6 is solution treated and precipitation heat treated in an oven, this is also called artificial aging.
Now to bring a T0 back to T6, you have to solution treat at 970°F +/- 10°F, hold for 35 minutes and then quench in water. Follow this with the precipitation cycle which is 350°F +/- 10°F for 8 hours, the so-called artificial age.

John

 

[CoryPad]

There is no such thing as T0 temper.

Annealed material is in the O temper.

According to MIL-H-6088 (free at the ASSIST web site), annealing for 6061 is done at 760 [°]F for 2 to 3 hours.

If you want T6 temper from O temper, you must re-solutionize, quench and age. This would be:

solutionize at 960 to 1075 [°]F for 30 min (for air furnace and based on your thickness)

quench

artificially age at 310 to 330 [°]F for 18 hours

 

[davidlight]

Thanks Jsokal and CoryPad for your replies. Is that info published anywhere? I need something to reference.

Thanks

David

 

[TVP]

davidlight,

Yes, this information is widely published. The following are either consensus standards or reputable handbook references that contain this information:


MIL-H-6088 (no longer official, has been replaced by SAE-AMS-H-6088)

http://assist.daps.dla.mil/quicksearch/basic_profile.cfm?ident_number=5791

SAE AMS 2772 Heat Treatment of Aluminum Alloy Raw Materials

http://www.sae.org/technical/standards/AMS2772E

SAE AMS 2770 Heat Treatment of Wrought Aluminum Alloy Parts

http://www.sae.org/technical/standards/AMS2770H

ASTM B 918/B 918M Standard Practice for Heat Treatment of Wrought Aluminum Alloys

http://www.astm.org/Standards/B918.htm

ASM HANDBOOK Volume 4 Heat Treating, "Heat Treating of Aluminum Alloys", pages 841-879

http://asmcommunity.asminternational.org/portal/site/

http://www/menuitem.2b9d1953d012ee1...VgnVCM100000701e010aRCRD&itemId=asmhba0001205