EFI Alloy 50 (High Permeability 49®) Heat Treatment
In-Process Annealing
- To relieve all strains and restore EFI Alloy 50 (High Permeability 49®) to a soft condition suitable for drawing, spinning, forming, bending and similar operations, anneal for not more than one hour at 1450°/1600°F (788°/871°C).
- High nickel, high permeability alloys readily absorb carbon, oxygen, sulfur, and other contaminants from combustion furnace gases. It is recommended that in-process annealing be done in a hydrogen or inert gas atmosphere.
Ferromagnetic Standard Hydrogen Annealing
- Prior to annealing all oil, grease, lacquer and any contaminants must be removed from the alloy.
- Separate individual parts by an inert insulating powder (aluminum oxide or magnesium) or surface insulation media during the hydrogen anneal process.
- To achieve optimum magnetic and electrical properties including maximum softness, EFI Alloy 50 (High Permeability 49®) 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 2150°F (1177°C).
- Follow by a furnace cool rate of 100°/200°F (55°/110°C) per hour down to 800°F (427°C) and at any rate afterwards.