What is the difference between the yield point and the elastic limit?

[Abu]

I don't understand the difference between the elastic limit and the yield point. I understand that if you stretch a material within the elastic limit, then the material should return to its normal shape. However, the yield point is described as the point at which a permanent increase in length is obtained. So shouldn't the elastic limit and the yield point be the same point on a force by length graph? In the graph the yield point is further past the elastic limit.

Thank you.

 

[DoItForYourself]

You are right.

Generally, elastic limit is an alternative name for yield point (or yield stress). The distinction of the two points seems weird.

 

[JRMichler]

Since the elastic limit is difficult to find exactly, the yield point is usually defined as 0.2% yield. That's a lot easier to measure, and thus more reproducible.