INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

Effect of Elevated Temperature on UTS of Aluminium

Effect of Elevated Temperature on UTS of Aluminium

(OP)
I have a question regarding the degradation in mechanical properties of 6061-T6 aluminium alloy at elevated temperatures.

The application involves operation at 250degC which creates quite a severe reduction in the strength properties. If I review published data (ESDU, MMPDS-4 etc) there are heat factor curves typically for 1hr, 10hr, 1000hr and 10,000hr soak times. For my application it will only be subjected to the elevated temperature for a maximum of 10-hours in any usage cycle. However, over the life of the vehicle the total exposure time will run into thousands of hours.

My interpretation is that the 10-hour curve should be used as this is the maximum soak time. However, I have had conflicting advice that the effect is cumulative and therefore the 10,000-hour curve should be used. At the operating temperatures at which this equipment is exposed this will make a big difference in the allowable strength properties.

Any advice gratefully received!

Peter

RE: Effect of Elevated Temperature on UTS of Aluminium

You need to consider the total cumulative time for this application.
Use the 10,000 hr curve.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Effect of Elevated Temperature on UTS of Aluminium

Over-aging would be cumulative damage because this is an age hardenable material.

RE: Effect of Elevated Temperature on UTS of Aluminium

(OP)
Thanks for the replies. To err on the safe side I probably need to stick with the 10,000-hour curve

RE: Effect of Elevated Temperature on UTS of Aluminium

SlipperyPete...

Aluminum is a VERY poor choice for material in the temperature range You've noted... especially 6061.

6061-T6 is service rated ~300F... but anything more than VERY short spikes [a few minutes] at 250C/485F will degrade it to an oxidized and annealed condition very swiftly.

The only structural material I am aware of that can sustain operational temps at 350F [barely] is 2219-T6... and that should be anodized or [better] IVD [pure] aluminum coated to minimize oxidation.

Unsure what aluminum alloys are used for high performance pistons... but they would be 'best suited' for sustained high temp/stress operations.... but 485F is a sketchy 'stretch' for any aluminum alloy.

HOWEVER IF You really see a steady 485F, and minimum mass combined with strength/stiffness retention is required, then You need to consider titanium or steel alloys... with anodic, metallic or ceramic coatings for an oxidizing atmosphere.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

RE: Effect of Elevated Temperature on UTS of Aluminium

(OP)
Many thanks for your response Wil. I intend to argue against the use of this material and will use your response as additional ammunition!

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close