The Young’s Modulus of a material is a fundamental property of every material that cannot be changed.  It is dependent upon temperature and pressure, however.

The Young’s Modulus (or Elastic Modulus) is, in essence, the stiffness of a material. In other words, it is how easy it is bent or stretched.

The physics and numerical values are worked out like this:

Young’sModulus \( =\frac{\text {Stress}}{\text {Strain}} \)

where:

Stress \( =\frac{\text { Force }}{\text { Cross }-\text { Sectional Area }} \)
Strain\( =\frac{\text {Change in length}}{\text {Original length}} \)

when graphed, the resulting plot will look something similar to this:

Young’s modulus is the slope of the initial section of the curve (i.e.  m in \( y=m x+b \))

When a material reached a certain stress, the material will begin to deform.  It is up to the point where the structure of the material is stretching and not deforming.  However, if you are to stress the material more than this, the molecules or atoms inside will begin to deform and permanently change the material.

A good analogy to this would be a rubber band:  when you stretch a rubber band, you are not deforming it, but stretching it.  However, if you pull it too hard, the rubber band will begin to deteriorate or deform.  Usually, when this happens, it is not too much longer until it breaks.