What causes some materials to have upper and lower yield points?

[||spoon||]

Hey,

Just wondering how to explain the yield point run-off for low carbon steel. Why does LCS have an upper yield point, followed directly by a lower yield point?

Thanks,

-Spoon

[Mapes]

Answered recently here (http://www.physicsforums.com/showpost.php?p=2605350&postcount=8).

[||spoon||]

Thats what i thought ;)

Thanks