| Carpenter
High Permeability "49" |
| Type
Analysis: Carbon...........................0.05%
Manganese....................0.05%
Silicon............................0.35%
Nickel.............................48.0%
Iron..............................Balance
DESCRIPTION:
Carpenter High Permeability "49" is 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. It is used in laminated cores for instrument transformers,
magnetic shields and cores for certain electronic and communication 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 is used in solenoid
cores in light, sensitive relays that must operate and respond to weak currents that
induce low magnetizing forces.
After it is given a low temperature hydrogen anneal, 1300/1400ºF
(704/706ºC), High Permeability "49" exhibits constant permeability
characteristics. Its initial permeability is approximately 1000 and it will remain close
to this value at flux densities up to approximately 500 gausses.
Carpenter High Permeability "49" is available in three
grades. Two of these - High Permeability "49" and High Permeability
"49" Rotor Grade – show minimum directional magnetic properties.
High Permeability "49" is available as bars, wire, rod and
strip in thicknesses of 0.020" (0.05 cm) and over. Its major uses include magnetic
shields and solid cores for solenoids and other control devices. |
High Permeability "49" Rotor Grade is supplied as un-oriented
strip for laminations 0.004/0.020"(0.010/0.051 cm) thick. It is usually used in
rotating components such as resolvers and servo-synchros whose magnetic properties must be
nondirectional.
Carpenter High Permeability "49" – Transformer Grade is
specially processed to produce higher permeabilities at low magnetizing forces in the
directions parallel to, and perpendicular to the rolling direction. It is available in
strip 0.004/0.020" (0.010/0.051 cm) thick. Its primary application is for transformer
laminations.
PHYSICAL CONSTANTS:
Specific
gravity..................................8.250
Density –
lb/in³....................................0.298
Mean coefficient of thermal expansion
in/in/ºF x 10--6
(77/400ºF)....................5.20
cm/cm/ºC x 10--6 (25/204ºC)..............
9.40
Electrical resistivity
ohm-cir mil/ft 290
microhm-cm 48
Temperature coefficient of electrical resisitivity
per ºF (0/930ºF) 0.002
per ºC (-17.8/499ºC) 0.0036
Specific heat
BTU/lb/ºF 0.12
kcal/kg/ºC 0.12
Thermal conductivity
BTU/in/ft²/hr/ºF 90.0
kcal/m/hr/ºC 11.2
Curie temperature.....................840/930ºF (449/499ºC)
Melting point.............................2600ºF (1427ºC)
|
MAGNETIC PROPERTIES:
Grade |
Thickness |
Minimum 60 Cycle AC Permeability |
inches |
cm |
B40 |
B200 |
B2000 |
B4000 |
B8000 |
| Rotor |
0.014 |
0.036 |
6,000 |
10,000 |
26,000 |
37,000 |
41,500 |
| Transformer |
0.014 |
0.036 |
10,000 |
14,500 |
32,000 |
40,000 |
45,000 |
| Rotor |
0.006 |
0.015 |
6,500 |
11,000 |
32,000 |
45,000 |
60,000 |
| Transformer |
0.006 |
0.015 |
11,000 |
17,000 |
46,000 |
56,000 |
62,000 |
These minimum permeability requirements are based on
evaluating the properties via a ring specimen 1½"(3.81 cm) OD x 1" (2.54 cm) ID
hydrogen annealed at 2150ºF (1177ºC) four hours and furnace cooled with an approximate
cooling rate of 150/220ºF (83/122 Cº) per hour through the Curie Point. |
 |
 DC Magnetic Properties determined according
to ASTM A-341.
|
Bars |
Strip 0.025"
(0.064 cm)
To 0.125" (0.318cm) |
Initial Permeability B100
Maximum Permeability
Residual Magnetism,
Gausses
Coercive Force, Oersteds
from 10,000 Gausses
from 5,000 Gausses
Saturation Inductance from H-100 Oersteds, Gausses
|
5,000
50,000
6,000
0.05/0.10
0.02/0.03
15,000
|
6,500
60,000
9,000
0.05/0.08
0.02/0.03
15,000
|
Temperature Variation of Permeability
(Expressed in % of Value at 77ºF (25ºC).
Temperature |
Permeability at
1000 Gausses |
Maximum
Permeability |
ºF |
ºC |
-94 |
-70 |
75/90 |
90/95 |
212 |
100 |
120/130 |
100/105 |
AC and DC Magnetic Properties of
lamination strip 0.006" (0.015 cm) and .014" (0.036 cm) thick.
HEAT TREATMENT:
Strain Relieving Anneal: 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 1450/1600ºF (788/871ºC). Since 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 a hydrogen or inert gas atmosphere. |
Standard Hydrogen Anneal: For
maximum softness and optimum magnetic and electrical properties, High Permeability
"49" should be annealed in an oxygen-free, dry hydrogen atmosphere with a dew
point below -40ºF (-40ºC) for two to four hours at 2150ºF (1177ºC),followed with a
furnace cool of 100/200ºF (38/93ºC) per hour down to 800ºF (427ºC) and any rate
thereafter. Oil, grease, lacquer and all other contaminants must be removed before
annealing. The individual parts should be separated by an inert insulating powder such as
magnesium or aluminum oxide during hydrogen annealing or surface insulation media.
WORKABILITY:
Machinability: If components are to be machined in volume from bar
stock, High Permeability "49-FM", a free machining grade, is recommended.
The regular grade, High Permeability "49", machines some-what
like 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 is recommended for drilling and
machining operations which must be done at slow speeds. Work hardened bars (Rockwell B
85/100 minimum) offer best machining characteristics. Parts should be degreased and
cleaned as soon as possible.
Cold Forming: For best blanking characteristics, strip should be
purchased in the cold rolled condition, Rockwell B 90 minimum. For best forming
characteristics, strip should be purchased as cold rolled annealed for forming. Best
drawing characteristics are obtained when strip is purchased as annealed, Deep Drawing
Quality.
Forging: The recommended forging temperature for High
Permeability "49" is 2150ºF (1177ºC).
Welding: It is readily brazed, welded, soft and hard soldered by
following the usual practices for ferrous alloys.
CORROSION RESISTANCE:
High Permeability "49" resists weather and moisture corrosion
to a moderate extent.
FORMS AVAILABLE:
Strip, cold rolled or annealed
Wire, cold drawn
Bars, hot rolled, cold drawn and centerless ground
Billets for forging
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