Type Analysis | Description | Applications | Corrosion Resistance
Physical Properties | Magnetic Properties | Heat Treatment | Workability | Typical Mechanical Properties

Type Analysis

Description

High Permeability "49" alloy is a 48% nickel-iron alloy which has a saturation flux density of approximately 15,000 gausses after hydrogen annealing. Hysteresis loss is very low in either DC or AC circuits in which the frequency is less than 400 cycles per second.
Following a low temperature hydrogen anneal at 1300/1400°F (704/760°C), alloy 49 exhibits constant permeability characteristics. Its initial permeability is approximately 500 gausses.

Application

High permeability "49" alloy has been used in laminated cores for instrument transformers, magnetic shields and cores for certain electronic and communications devices in which extremely high permeability at low magnetizing forces greatly increases the efficiency and effectiveness of the equipment. Because of its high permeability, it has also been used in solenoid cores in light, sensitive relays that must operate and respond to weak currents that induce low magnetizing forces.

Corrosion Resistance

High Permeability "49" alloy resists weather and moisture corrosion to a moderate extent.

Physical Properties

Specific gravity..........................................8.18                             Electrical resistivity
Density                                                                                            ohm c/mf................................ 290
   lb/cu in............................................... 0.295                                 microhm-mm.......................... 480
   kg/cu m............................................... 8249                            Temperature coefficient of electrical
Thermal conductivity                                                                   resistivity
   Btu-in/ft²/hr/°F........................................ 90                                  per °F(0/930°F)...................0.002
   W/m-K.................................................... 13                                  per  °C(-17.8/499°C)........ 0.0036
Mean coefficient of thermal expansion                                        Melting point
   x 10(-6)/°F(77/400°F)............................ 4.6                                 °F.......................................... 2600
   x 10(-6)/°C(25/204°C)............................ 8.3                                 °C......................................... 1427
Curie temperature                                                                          Specific heat
    °F................................................... 840/930                                  Btu/lb-°F.............................. 0.12
    °C................................................... 449/499                                  kJ/kg-K................................ 0.50

Magnetic Properties

DC Magnetic Properties
Determined according to ASTM-A-596

Temperature Variation of Permeability
Expressed in % of value of 77°F (25°C). AC and DC magnetic properties of lamination strip 0.006" and 0.014" thick

Heat Treatment

Strain Relieving Anneal
To relief all strains and restore the alloy to a soft condition suitable for drawing, spinning, forming, bending and similar operations, anneal for not more than 1 hour at 1450/1600°F .
Since high-nickel, high permeability alloys readily absorb carbon, sulfur, oxygen and other contaminants from combustion furnace gasses, in-process annealing should be done in a hydrogen or inert gas atmosphere.

Standard Hydrogen Anneal
For maximum softness and optimum magnetic and electrical properties, High Permeability "49" alloy should be annealed in an oxygen-free, dry hydrogen atmosphere with a dew point below -40°F (-40°C) for 2 to 4 hours at 2150°F (1177°C), followed by a furnace cool at a rate of 100/200°F (38/93°C) per hour down to 800°F (427°C) and at any rate thereafter.
Oil, grease, lacquer and any other contaminants must be removed before annealing. During hydrogen annealing, the individual parts should be separated by a surface insulation media or an inert insulating powder, such as magnesium or aluminum oxide.

Workability

Machinability
If components are to machined in volume from bar stock, High Permeability "49"-FM, a free-machining grade, is recommended. The standard grade , High Permeability "49" alloy, machines somewhat like the austenitic stainless alloys. It develops gummy chips but does not work harden as rapidly as the stainless alloys. Sulfur-bearing cutting compounds are highly detrimental to the final magnetic properties. Animal lard oil should be used in drilling and machining operations which must be performed at low speeds. Work hardened bars offer the best machining characteristics. Parts should be degreased and cleaned as soon as possible.
Suggested speeds for machining alloy 49 are contained in the following chart:

* When using carbide tools, surface speed feet/minute (sfm) can be increased between 2 to 3 times over the high-speed tool suggestions. Feeds can be increased between 50 and 100%.
Figures used for all metal removal operations reported are average. On certain work, the nature of the part may require adjustment of the speeds and feeds. Each job has to be developed for best production results with optimum tool life. Speeds or feeds should be increased or decreased in small steps.

Cold forming
For best blanking characteristics, strip should be ordered in the cold rolled condition at Rockwell B90 minimum. For best forming characteristics, strip should be ordered as cold rolled and annealed for forming. Best drawing characteristics are obtained when ordered as annealed, deep drawing quality.

Forging
The recommended forging temperature is 2150°F (1177°C).

Welding
Alloy 49 is readily blazed, welded and soft or hard soldered by employing the usual practices used on ferrous alloys.

Typical Mechanical Properties

Bar

Strip

Effect of Heat Treating Temperature on Typical Mechanical Properties
Strip 0.060" (1.52 mm) thick heat treated for 2 hours at indicated temperature

Invar 49 - Current Inventory Stock

Type Analysis | Description | Applications | Corrosion Resistance
Physical Properties | Magnetic Properties | Heat Treatment | Workability | Typical Mechanical Properties

Type Analysis

Description

High Permeability "49" alloy is a 48% nickel-iron alloy which has a saturation flux density of approximately 15,000 gausses after hydrogen annealing. Hysteresis loss is very low in either DC or AC circuits in which the frequency is less than 400 cycles per second.
Following a low temperature hydrogen anneal at 1300/1400°F (704/760°C), alloy 49 exhibits constant permeability characteristics. Its initial permeability is approximately 500 gausses.

Application

High permeability "49" alloy has been used in laminated cores for instrument transformers, magnetic shields and cores for certain electronic and communications devices in which extremely high permeability at low magnetizing forces greatly increases the efficiency and effectiveness of the equipment. Because of its high permeability, it has also been used in solenoid cores in light, sensitive relays that must operate and respond to weak currents that induce low magnetizing forces.

Corrosion Resistance

High Permeability "49" alloy resists weather and moisture corrosion to a moderate extent.

Physical Properties

Specific gravity..........................................8.18                             Electrical resistivity
Density                                                                                            ohm c/mf................................ 290
   lb/cu in............................................... 0.295                                 microhm-mm.......................... 480
   kg/cu m............................................... 8249                            Temperature coefficient of electrical
Thermal conductivity                                                                   resistivity
   Btu-in/ft²/hr/°F........................................ 90                                  per °F(0/930°F)...................0.002
   W/m-K.................................................... 13                                  per  °C(-17.8/499°C)........ 0.0036
Mean coefficient of thermal expansion                                        Melting point
   x 10(-6)/°F(77/400°F)............................ 4.6                                 °F.......................................... 2600
   x 10(-6)/°C(25/204°C)............................ 8.3                                 °C......................................... 1427
Curie temperature                                                                          Specific heat
    °F................................................... 840/930                                  Btu/lb-°F.............................. 0.12
    °C................................................... 449/499                                  kJ/kg-K................................ 0.50

Magnetic Properties

DC Magnetic Properties
Determined according to ASTM-A-596

Temperature Variation of Permeability
Expressed in % of value of 77°F (25°C). AC and DC magnetic properties of lamination strip 0.006" and 0.014" thick

Heat Treatment

Strain Relieving Anneal
To relief all strains and restore the alloy to a soft condition suitable for drawing, spinning, forming, bending and similar operations, anneal for not more than 1 hour at 1450/1600°F .
Since high-nickel, high permeability alloys readily absorb carbon, sulfur, oxygen and other contaminants from combustion furnace gasses, in-process annealing should be done in a hydrogen or inert gas atmosphere.

Standard Hydrogen Anneal
For maximum softness and optimum magnetic and electrical properties, High Permeability "49" alloy should be annealed in an oxygen-free, dry hydrogen atmosphere with a dew point below -40°F (-40°C) for 2 to 4 hours at 2150°F (1177°C), followed by a furnace cool at a rate of 100/200°F (38/93°C) per hour down to 800°F (427°C) and at any rate thereafter.
Oil, grease, lacquer and any other contaminants must be removed before annealing. During hydrogen annealing, the individual parts should be separated by a surface insulation media or an inert insulating powder, such as magnesium or aluminum oxide.

Workability

Machinability
If components are to machined in volume from bar stock, High Permeability "49"-FM, a free-machining grade, is recommended. The standard grade , High Permeability "49" alloy, machines somewhat like the austenitic stainless alloys. It develops gummy chips but does not work harden as rapidly as the stainless alloys. Sulfur-bearing cutting compounds are highly detrimental to the final magnetic properties. Animal lard oil should be used in drilling and machining operations which must be performed at low speeds. Work hardened bars offer the best machining characteristics. Parts should be degreased and cleaned as soon as possible.
Suggested speeds for machining alloy 49 are contained in the following chart:

* When using carbide tools, surface speed feet/minute (sfm) can be increased between 2 to 3 times over the high-speed tool suggestions. Feeds can be increased between 50 and 100%.
Figures used for all metal removal operations reported are average. On certain work, the nature of the part may require adjustment of the speeds and feeds. Each job has to be developed for best production results with optimum tool life. Speeds or feeds should be increased or decreased in small steps.

Cold forming
For best blanking characteristics, strip should be ordered in the cold rolled condition at Rockwell B90 minimum. For best forming characteristics, strip should be ordered as cold rolled and annealed for forming. Best drawing characteristics are obtained when ordered as annealed, deep drawing quality.

Forging
The recommended forging temperature is 2150°F (1177°C).

Welding
Alloy 49 is readily blazed, welded and soft or hard soldered by employing the usual practices used on ferrous alloys.

Typical Mechanical Properties

Bar

Strip

Effect of Heat Treating Temperature on Typical Mechanical Properties
Strip 0.060" (1.52 mm) thick heat treated for 2 hours at indicated temperature

Invar 49 - Current Inventory Stock