Over-aging Aluminum 6061-T6511 2

[metalman8357]

Hi all,

I have two different sizes of round aluminum bars that are both 6061-T6511. The bars are 12" in length and are 2.625" and 2.375" in diameter respectively. I need to over-age these samples so that the tensile strength is within 38-45 ksi, and the yield strength is within 35-42ksi (or at least close to these ranges). Currently, the 2.625" round bars have a tensile strength of 50.5 ksi and a yield of 46.3 ksi. The 2.375" round bars have a tensile strength of 49.2 ksi and a yield of 45.1 ksi. I couldn't find a good resource on how to calculate time and temperature to overage these samples. Any suggestions? I'd rather not have to play trial and error since I don't have any samples to spare.

Thanks,
M

 

[metalman8357]

Couldnt find anything useful in ASM volume 4...

 

[CoryPad]

Looks like you need the strength to be 0.8 times the current strength. MIL-HDBK-5, Figure 3.6.2.2.1a shows you would need 30 minutes at 300 degrees F.

 

[metengr]

I believe the graph referenced above is percent tensile strength of room temperature during exposure to elevated temperature, and is not strength at room temperature. In other words, the 6061 material is being tested between 200-700 deg F to determine elevated temperature strength properties. What you need are graphs or data showing the UTS at RT as a function of exposure to either extended ageing time or a temperature above the original aging temperature at x time to achieve your 80% of RT TS.

 

[CoryPad]

Metengr is correct, I misread the graph. ASM Handbook Volume 2 has a graph that shows that 1 hour at 400 degrees F would put the material around 38 ksi.

 

[metalman8357]

CoryPad, what figure are you referring to in Volume 2?

 

[metalman8357]

Also, I have an oven that will hit 300F and I'd rather not send it out to our furnaces. How long would it take at this temperature?

 

[metengr]

Look in Volume 2, under Aluminum Mill and Engineered Products - Physical Metallurgy
Fig. 12 Precipitation heat treatment or artificial aging curves for solution heat-treated aluminum alloy 6061

 

[mighoser]

Looking at NASA Materials Data HDBK for AL6061. 425F for a half hour looks like it should get you within the ranges you desire.