Does Heat Treatment Affect Elasticity? Investigating Changes in Young's Modulus

[Dionisius DH]

Homework Statement

The experiment :
How the elasticity of material might change under heat treatment?
The experiments conducted in two different way, first one the hot bobby pin set to cool down slowly after heated (the professor called annealing treatment), and the second one the pin set to cool down rapidly in the water (called quenching). Why does this phenomenon happen?

Homework Equations

Y = σ/ ε
ε = ΔL / Lo
σ = F/A

The Attempt at a Solution

Some sources said that Young's Modulus is affected by heat treatment because Young's modulus has its origin in the nature of bonding including interatomic distances, some others said that it doesn't affect Young's Modulus.

 

[Bystander]

Your thoughts?