ASTM A901-97
(Specification)Standard Specification for Amorphous Magnetic Core Alloys, Semi-Processed Types
Standard Specification for Amorphous Magnetic Core Alloys, Semi-Processed Types
SCOPE
1.1 This specification covers the general requirements to which flat-cast, amorphous, semi-processed, iron-base magnetic core alloys must conform.
1.2 These alloys are produced by a rapid-quenching, direct-casting process, resulting in metals with non-crystalline structure. The metallic alloys are made to meet specified maximum core-loss values and are intended primarily for commercial power frequency (50 and 60 Hz) applications in magnetic devices. Desirable core-loss and permeability characteristics are developed by further heat treatment in a magnetic field by the buyer. The heat treatment typically consists of heating the material to a temperature of 320 to 420°C in a dry, inert atmosphere for 5 to 10 min. A magnetic field may be required during annealing as designated by the manufacturer. Exact optimum annealing conditions depend on the processing of the material and the size and shape of the device.
1.2.1 The chemical, magnetic, and physical properties are listed for reference only. They are typical values for a particular alloy and do not constitute a standard specification for that alloy.
1.3 Some of these alloys are sensitive to mechanical stress. Care must be exercised in minimizing any stresses on the material in its final application, otherwise, its magnetic properties will be impaired significantly.
1.4 This specification is developed to aid in the purchase of transformer grade amorphous strip. It provides the chemical, physical, and magnetic parameters and procedures for quality control tests. Note-For more information on procedures associated with this specification, refer to the following: Practices A34, A664, A700, and B490; Test Methods A370 and A773.
1.5 This standard does not purport to address the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: A 901 – 97
Standard Specification for
Amorphous Magnetic Core Alloys, Semi-Processed Types
This standard is issued under the fixed designation A 901; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
NOTE 1—For more information on procedures associated with this
1. Scope
specification, refer to the following: Practices A 34, A 664, A 700, and
1.1 This specification covers the general requirements to
B 490; Test Methods A 370 and A 773.
which flat-cast, amorphous, semi-processed, iron-base mag-
1.6 This standard does not purport to address the safety
netic core alloys must conform.
concerns associated with its use. It is the responsibility of the
1.2 These alloys are produced by a rapid-quenching, direct-
user of this standard to establish appropriate safety and health
casting process, resulting in metals with noncrystalline struc-
practices and determine the applicability of regulatory limita-
ture. The metallic alloys are made to meet specified maximum
tions prior to use.
core-loss values and are intended primarily for commercial
power frequency (50- and 60-Hz) applications in magnetic
2. Referenced Documents
devices. Desirable core-loss and permeability characteristics
2.1 ASTM Standards:
are developed by further heat treatment in a magnetic field by
2 A 34 Practice for Sampling and Procurement Testing of
the purchaser. The heat treatment typically consists of heating
Magnetic Materials
the material to a temperature of 320 to 420°C in a dry, inert
A 340 Terminology of Symbols and Definitions Relating to
atmosphere for 5 to 10 min, although soak times of up to 2 h
Magnetic Testing
may be used for large transformer cores. A magnetic field may
A 370 Test Methods and Definitions for Mechanical Testing
be required during annealing as designated by the producer.
of Steel Products
Exact optimum annealing conditions depend on the processing
A 664 Practice for Identification of Standard Electrical- and
of the material and the size and shape of the device.
Lamination- Steel Grades in ASTM Specifications
1.3 Some of these alloys are sensitive to mechanical stress.
A 700 Practices for Packaging, Marking, and Loading
Care must be exercised in minimizing any stresses on the
Methods for Steel Products for Domestic Shipment
material in its final application, otherwise, its magnetic prop-
A 712 Test Method for Electrical Resistivity of Soft Mag-
erties will be impaired significantly.
netic Alloys
1.4 This specification is developed to aid in the purchase of
A 773 Test Method for D-C Magnetic Properties of Mate-
transformer grade amorphous strip. It provides the chemical,
rials Using Ring and Permeameter Procedures with D-C
physical, and magnetic parameters and procedures for quality
Electronic Hysteresigraphs
control tests.
A 900 Test Method for Lamination Factor of Amorphous
1.5 The values stated in either customary (cgs-emu and
Magnetic Strip
inch-pound) units or SI units are to be regarded separately as
B 490 Practice for Micrometer Bend Test for Ductility of
standard. Within the text, the SI units are shown in brackets.
Electrodeposits
The values stated in each system are not exact equivalents;
C 693 Test Method for Density of Glass by Buoyancy
therefore, each system shall be used independently of the other.
D 3455 Test Methods for Compatibility of Construction
Combining values from the two systems may result in noncon-
Materials with Electrical Insulating Oil of Petroleum
formance with this specification.
Origin
3. Terminology
This specification is under the jurisdiction of ASTM Committee A-6 on
3.1 The terms and symbols used in this specification are
Magnetic Properties and is the direct responsibility of Subcommittee A06.02 on
Material Specifications.
Current edition approved June 10, 1997. Published December 1997. Originally
published as A 901 – 90. Last previous edition A 901 – 90. Annual Book of ASTM Standards, Vol 03.04.
2 4
The process of heat treatment in a magnetic field is covered by a patent held by Annual Book of ASTM Standards, Vol 01.03.
General Electric Co. Interested parties are invited to submit information regarding Annual Book of ASTM Standards, Vol 01.05.
the identification of acceptable alternatives to this patented item to the Committee Annual Book of ASTM Standards, Vol 02.05.
on Standards, ASTM Headquarters. Your comments will receive careful consider- Annual Book of ASTM Standards, Vol 15.02.
ation at a meeting of the responsible technical committee, which you may attend. Annual Book of ASTM Standards, Vol 10.03.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
A 901
defined in Terminology A 340. 7.6 Lamination Factor—The minimum lamination factor of
uncoated material shall be 77 % as measured in accordance
4. Dimensions
with Test Method A 900. The lamination factor for coated
4.1 Width—Tolerances on nominal as-cast strip shall be material shall be as agreed between the producer and the
+0.004, −0.020 in. [+0.1 mm, −0.5 mm] from specified
purchaser.
purchase width. 7.7 Surface—The strip surface and edges shall have no
4.2 Thickness—The nominal thickness shall be 0.001 in.
wrinkles, dimples, cracks, folds, flakes, or other injurious
[0.025 mm] as measured by a 0.25-in. [6.35-mm] diameter imperfections that would make the material unsuitable for the
anvil micrometer. The nominal thickness may vary 60.0002
fabrication of transformer cores.
in. [60.005 mm], but the maximum thickness variation across 7.8 Edge—The strip edge shall have no slivers with a
the width shall be within 610 % of the mean thickness, or as
maximum dimension exceeding 0.004 in. [0.1 mm].
agreed upon between the purchaser and the producer. 7.9 Camber—The strip edge shall show no excessive lateral
curvature (camber). Maximum deviation from a straight line of
5. Material Requirements
an 8-ft [2.4-m] strip edge shall not exceed 0.1 in. [2.5 mm].
5.1 Amorphous magnetic core alloys are composed princi-
7.10 Pinholes—The strip shall have no pinholes exceeding
pally of iron with small amounts of alloying elements such as
0.08 in. [2.0 mm]. Maximum hole frequency, visible against a
2 −4
boron and silicon. Other chemical elements are in residual
light source, shall not be more than 1 per 3 in. [19.4 3 10
amounts or can be added to improve fabrication or the physical
m ].
or magnetic properties. The producer shall provide, on request,
8. Magnetic Property Requirements
a statement of the nominal chemistry being supplied. The
nominal composition for one particular alloy, in weight per-
8.1 Test Procedure—The magnetic quality of each batch of
cent, is: iron 92, silicon 5, and boron 3. material (as defined in 6.1) shall be determined by obtaining
test samples from both ends of a batch (or lot). These samples
6. Sampling
shall be annealed in a dry, inert atmosphere with an applied
6.1 A continuously cast strip in one coil without breaks will magnetic field of at least 10 Oe [800 A/m] using the time and
constitute one test lot. In practice, this may represent quantities
temperature sequence recommended by the producer. The
up to 2200 lb [1000 kg], depending on the width of the strip. samples may be either in toroidal or flat strip form as agreed
6.2 Test samples normally shall be taken from both ends of
upon between the producer and the purchaser.
the continuous strip of each test lot. Other sample frequencies 8.2 Amorphous magnetic core alloys are purchased to
may be used as agreed upon by the producer and the purchaser.
specified maximum core loss requirements. The purchaser
6.3 For small coils, less than 100 lb [45 kg], and for coils shall make clear to the producer the limitin
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