Hollomon-Jaffe parameter

The Hollomon-Jaffe parameter, or HP, describes the effect of a heat treatment at a temperature for a certain time.

Effect

The effect of the heat treatment depends on its temperature and its time. The same effect can be achieved with a low temperature and a long holding time, or with a higher temperature and a short holding time.

Formula

In the Hollomon-Jaffe parameter, This exchangability of time and temperature can be described by the following formula:

:$H\_p\; =\; frac\; \{(273.15\; +\; T)\}\{1000\}\; cdot\; (C\; +\; log(t))$

This formula is not consistent concerning the units; the parameters must be entered in a certain manner. The argument of the logarithmic function has the unit minutes. C is a parameter unique to the material used. The Hollomon parameter itself is unitless and realistic numeric values vary between 15 and 21.