Ferromagnetic Annealing and In-Process Heat Treating
There are many trade names for the soft magnetic alloys. Ed Fagan Inc stock HyMu 80®, Hipernom®, High Permeability 49® (aka High Perm 49®/49FM®), Magnifer® 7904, Magnifer® 50, Moly Permalloy®, Permalloy 80® and Alloy 47-50®. Ed Fagan Incorporated buys from the manufacturers of all these alloys and markets them as EFI Alloy 79 and EFI Alloy 50. Should you require metal made by a specific manufacturer please let us know and we will comply.
- To relieve all strains and restore the alloy to a soft condition suitable for drawing spinning, forming, bending and similar operations, anneal for not more than one hour at 1450°/1850°F (788°/1010°C).
- High nickel, high permeability alloys readily absorb carbon, sulfur, oxygen and other contaminants from combustion furnace gases. It is recommended that in-process annealing be done in dissociated ammonia, hydrogen, vacuum or inert gas atmosphere.
Ferromagnetic | Hydrogen Anneal
- For maximum softness and optimum magnetic and electrical properties, the alloy should be annealed in an oxygen free, dry hydrogen atmosphere with a dew point below -40°F (-40°C) for two to four hours at 2050°F (1121°C) to 2150ºF (1177°C).
- Furnace cool to 1100°F (593°C). From 1100º/700°F (593°/371°C) cool at a rate between 350°F (194°C) and 600°F (334°C) per hour.
- Oil, grease, lacquer and all other contaminants must be removed before annealing.
- The individual parts should be separated by an inert insulating powder (magnesium or aluminum oxide) during hydrogen annealing.
- Vacuum heat treating can be used. Generally there is a small sacrifice in magnetic properties compared to heat treating in a dry hydrogen atmosphere.