Yield vs elasticity in aluminum

[Ivan Seeking]

I have an application that involves forming 2024 aluminum in the T42 state. I need to determine [approximate] the amount of elastic stretch vs yield once the yield point has been exceeded. In other words, once beyond the yield point, how much of the strain results in addional yield, as opposed to additional elastic strain. As near as I can tell so far this will have to be determined empirically.

Additionally, I need to get a handle on the degree of work hardening [relative to the T value] that occurs with each bend.

Any information provided is greatly appreciated.

 

[Astronuc]

One needs the uniform elongation, which is the strain at which the material starts necking, which is around the ultimate tensile strength. Compare this to the strain at yield, which is mostly elastic, except for the 0.1% or 0.2% offset.

http://nd.edu/~manufact/MPEM%20pdf_files/Ch02.pdf

http://esminfo.prenhall.com/engineering/shackelford/closerlook/pdf/Shackelford_Ch6.pdf

 

[Ivan Seeking]

Aha! The return path follows the elastic slope. So Young's Modulus remains constant and a new elastic limit is defined.

Thank you very much, Astro. This was most helpful.