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Magnifer 7904 heat treatment

Magnifer 7904 heat treatment

Magnifer 7904 heat treatment

(OP)
Hello. Please help me understand the detail about the "Take-out-temperature " of the soft magnetics 7904 material. I don't fully understand the therm "Service temperature" at figure 7&8 site 7 of the data sheet
https://files.engineering.com/getfile.aspx?folder=...

I understand that it's very important for the final permeability but can't figure out exact procedure.
Thanks :)

RE: Magnifer 7904 heat treatment

Use figure 7&8.
What is your service temp?
Does your service depend more on initial perm or max perm?
Find the take out temp that matches your needs.
Then anneal at 1200C for 4 hrs, allow to cool in the furnace at a rate of 0.9C/min
And then remove and force air cool when you reach the desired take out temp.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Magnifer 7904 heat treatment

From the same datasheet, which is pretty much what I thought from the figures

Quote:

Different chemical compositions, especially in terms of the contents of the elements Ni and Mo, influence the most favourable annealing parameters such as the cooling rate and the take-out or tempering temperature in order to obtain optimum magnetic properties.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: Magnifer 7904 heat treatment

(OP)
Please correct me if I'm wrong."Service temperature" is nothing else but operating temperature?

RE: Magnifer 7904 heat treatment

exactly right about the temp

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Magnifer 7904 heat treatment

(OP)
So, if the part will operate at the service temperature 20-30c I should proceed with the take out @ 490-500c for the best magnetics properties?

RE: Magnifer 7904 heat treatment

Using 495C will give you the highest initial perm at your use temp.
And it is very close to the peek of the max perm also.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Magnifer 7904 heat treatment

(OP)
495c, thanks, clear. But looking at the cooling rate of 0.9k/min (4c/secomd, right?) it can be really tricky. Or I miss something here again?

RE: Magnifer 7904 heat treatment

You are correct, that is tricky.
At high temps that will require a programed ramp to not cool faster.
At low temps you may need to assist the cooling a little.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: Magnifer 7904 heat treatment

(OP)
All clear. Thanks guys

RE: Magnifer 7904 heat treatment

When we did alloys like this we always used forced convection furnaces.
Better uniformity and control.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

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