Strain hardening exponent

The strain hardening exponent (also called the strain hardening index), usually denoted formula_1, a constant often used in calculations relating to stress–strain behavior in work hardening. It occurs in the formula known as Hollomon's equation (after John Herbert Hollomon Jr.) who originally posited it as 
formula_2
where formula_3 represents the applied true stress on the material, formula_4 is the true strain, and formula_5 is the strength coefficient.
The value of the strain hardening exponent lies between 0 and 1. A value of 0 means that a material is a perfectly plastic solid, while a value of 1 represents a 100% elastic solid. Most metals have a n value between 0.10 and 0.50.