Question

stress-strain diagram of mild steel .
Describe Upper yield,lower yield. ​

Answer 1

Answer:

Upper yield point is the max load at which deformation starts, starting of deformation means dislocations are started moving in the material.

So this type of phenomenon is called permanent deformation by slip ( slip mechanism).

As the slip is taking place in the material , it offers less resistance to the material and hence curve falls slightly ( stress is the measurement of resistance offered by the material during the application of load).

And it reaches to some stress ( lower yiled point stress) which is the minimum stress required to maintain the deformation in the mateial.. And at the lower yield point for the low carbon steels ( mild steels) the stress strain cure is in some wave nature , this is because to break bonds with impurites while dislocations are moving out of the material , hence resistance increases and decreases periodically after that strain hardening takes place which increases resistance slowly by increasing of dislocations in the material...

Hope it will help..

Answer 2

Explanation:

stress-strain diagram of mild steel .

Describe Upper yield,lower yield.