EFI Alloy 79 (HyMu 80®) Heat Treatment
In-Process Anneal
- To relieve all strains and restore the EFI Alloy 79 (HyMu 80®) to a soft condition suitable for drawing, spinning, forming, bending or similar operations, anneal at 1450°/1850°F (788°/1010°C} for not more than one hour.
- EFI Alloy 79 (HyMu 80®) are high-nickel, high permeability alloys that will easily absorb contaminants, such as carbon, oxygen, and sulfur from combustion furnaces gasses. In-process annealing should be conducted in dissociated ammonia, hydrogen, vacuum or inert gas atmospheres.
Ferromagnetic Standard Hydrogen Annealing
- To achieve maximum softness including optimum magnetic and electrical properties, EFI Alloy 79 (HyMu 80®) should be annealed in an oxygen-free, dry hydrogen atmosphere with a dew point below -40°F (-40°C) at 2050°/2150°F (1121°/1177°C) for two to four hours. Furnace cool to 1100°F (593°C). From 1100° to 700°F (593° to 371°C) cool at a rate between 350° to 600°F (194° to 334°C) per hour.
- All oil, grease, lacquer and any other contaminants must be removed prior to annealing.
- Separate individual parts by an inert insulating powder (magnesium and aluminum oxide) during hydrogen annealing.
- Vacuum heat treating can be employed. Usually, there is some small sacrifice in magnetic properties compared to heat treating in a dry hydrogen atmosphere.