Hollomon-Jaffe given by Verypicky 1

[zirconium]

In continuation from Thread794-92824, I would like to know more about Jaffe-Hollomon parameter.
Does it exist: a similar equation for coppers and its alloys as the one that Verypicky gave (see below)?
VeryPicky, could you give me the reference of this equation?
I need it because I am converting the annealing program done with lab furnace to a production furnace.
Thanks in advance to you all for giving your opinion.

Hollomon and Jaffe formula:


(T+273)*(20+log(te))
HJ = -----------------------
1000


te = th + tc + t


T+273
th = ---------------------
2.3*h*(20-log(h))

T+273
tc = ---------------------
2.3*c*(20-log(c))

Where:
HJ - Hollomon/Jaffe parameter
T - holding temperature [°C]
te - effective holding time [h]
th - correction in holding time for heating cycle [h]
tc - correction in holding time for cooling cycle [h]
h - heating rate [°C/h]
c - cooling rate [°C/h]

 

[metengr]

zirconium;
The Hollomon Jaffe tempering parameter is a correlation of change in hardness of martensite in steels as a function of tempering temperature and time. This correlation was developed because the change in hardness of martensite is directly affected by carbide growth or coalescence and is a function of time at temperature using a Power Law function. To achieve the same hardness in martensite, either higher tempering temperature or shorter tempering times or lower tempering temperature and longer tempering times achieve the same results.

For materials that are not hardenable by heat treatment, the relationship above does not apply. Hardness increases from cold work or strain energy that is introduced during forming operations and is subsequently removed by exposure to an annealing heat treatment. Hardness changes as a function of grain growth and the release of strain energy upon exposure to elevated temperature.

For age (precipitation) hardening alloys, you have kinetics of nucleation and growth rates of precipitates as a function of time at temperature. This relationship is demonstrated by the Avrami Equation (aka C-curves related to phase transformations in metals). Since nucleation and growth rates are normally competing mechanisms, the size of the precipitate and volume fraction play a role in hardness.

 

[zirconium]

I agree 100% with you and therefore I need to know more about the Jaffe-Hollomon because I deal with aged hardenable copper alloys.
I am really interested to the equation given by VeryPicky because it takes into account the heating and cooling time.

 

[metengr]

Try a Google search and see if you can find any articles related to the Hollomon Jaffe tempering parameter. If you need more in depth information, ASM has an excellent book on the Induction Heat Treatment of Steel. Also, a second good reference is the Physical Metallurgy Handbook by Sihna.