Nitronic 50 Permeability / Anneal

[TJMAT]

Looking for reference for the annealing schedule for Nitronic 50 which minimizes permeability. I've seen 1950F to 2050F for 1 hour in vacuum but no cooling rate is specified (I suspect rapid cooling or water quench but I can't verify this). Does anyone have know of a more definitive reference for annealing of Nitronic 50? Always appreciate the assistance of experts - thank you.

 

[EdStainless]

If all that you care about is permeability I would use 2000F and cool as rapidly as practical.
The reason that people use vacuum is just to avoid oxidation.
Annealing in hydrogen would work just as well, if not better.
The other option is to air cool and then pickle to remove the oxides.

Just as a note, the higher anneal temp will lower the strength a little.
If you need less magnetic material you might look at Nitronic 40 (21-6-9).

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P.E. Metallurgy, Plymouth Tube

 

[MagBen]

I do not think the anneal temperature from 1950-2050F makes any difference in permeability.
This is a very stable austenitic SS, martensite induced ferromagnetism will be very limited due to high contents of Ni, Mn, N austenite formers. Anneal at any temperature gains no much in lowering perm. A tiny bit of ferromagnetism (Perm <1.01) probably comes from a tiny bit of remained ferrite.

Being said, the ferromagnetism could also origin from disorder/defects (say APBs), anneal can anneal out such disorders, leading to a bit lower permeability. Although the contribution from disorder is probably very low, it could be possible to decrease perm say from 1.006 to 1.005 (may or may not significant). So anneal and un-anneal could still make difference for this alloy already with a very low perm, but 1950 and 2050 make no difference because both are high enough to remove disorders.

 

[hacksaw]

Before you do any annealing, contact the material supplier.

A lot of what you do will depend on the final mechanical form, strength, and corrosion resistance requirements, an so on.