Strain-hardening exponent

The value n in the relationship = KEⁿ, where is the true stress; E is the true strain; and K, which is called the strength coefficient, is equal to the true stress at a true strain of 1.0. The strain-hardening exponent, also called n-value, is equal to the slope of the true stress/true strain curve up to maximum load, when plotted on log-log coordinates. The n-value relates to the ability of a sheet material to be stretched in metalworking operations. The higher the n-value, the better the formability (stretchability).

Source: The OHIO State University