Strain hardening exponent


The strain hardening exponent, noted as n, is a material's constant which is used in calculations for stress–strain behavior in work hardening. It occurs in the formula known as Hollomons equation after John Herbert Hollomon Jr. who originally proposed it:
σ = K ε n,

where σ represents the applied stress on the material,

ε is the strain,

and K 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.

Tabulation

MaterialnK
Aluminum 1100–O 0.20180
2024 aluminum alloy 0.16690
Aluminum 6061–O 0.20205
Aluminum 6061–T60.05410
Aluminum 7075–O 0.17400
Brass, Naval 0.49895
Brass 70–30 0.49900
Brass 85–15 0.34580
Cobalt-base alloy 0.502,070
Copper 0.54315
AZ-31B magnesium alloy 0.16450
Low-carbon steel 0.26530
4340 steel alloy 0.15640
304 stainless steel 0.4501275