2. Deformability: simplified diagram

We know that a metallic material subjected to tensile or shear stress has a deformation response that can be broken down into two additive, practically independent terms:

• elastic or reversible deformation, existing at any stress level (up to failure);

• plastic or irreversible deformation, which only occurs when local stress exceeds a critical value known as the elastic limit. This theoretical yield point should not be confused with the characteristic parameter known as the conventional yield point, derived from the tensile test and which attempts to represent it.