ASTM A901-19

Standard Specification for Amorphous Magnetic Core Alloys, Semi-Processed Types

ABSTRACT
This specification covers the requirements to which flat-cast, amorphous, semi-processed, iron-base magnetic core alloys must conform. These alloys shall be produced by a rapid-quenching, direct-casting process, resulting in metals with noncrystalline structure. The alloys shall be made to meet specified maximum core-loss values and shall be intended primarily for commercial power frequency applications. Desirable core-loss and permeability characteristics shall be developed by further heat treatment in a magnetic field. Amorphous magnetic core alloys are normally composed of iron with small amounts of alloying elements such as boron and silicon. There are no specific chemical requirements in this specification. Material produced to this specification shall conform to the required physical and mechanical properties such as density, ductility, thermal expansion, thermal conductivity, volume resistivity, lamination factor, surface, edge, and pinholes. The alloy shall also conform to the magnetic property requirements such as DC induction, DC coercive field strength, DC residual induction, core loss, and specific exciting power.
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 noncrystalline (amorphous) 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 user. 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, although soak times of up to 2 h may be used for large transformer cores. A magnetic field may be required during annealing as designated by the producer. Exact optimum annealing conditions depend on the processing of the material and the size and shape of the device.  
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 significantly impaired.  
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.  
1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses are numerical conversions to customary (cgs and inch-pound) units which are provided for information only and are not considered standard.  
1.6 This standard does not purport to address the safety concerns associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Jul-2019
• ICS: 29.030 - Magnetic materials
• ICS: 29.100.10 - Magnetic components
• Technical Committee: A06 - Magnetic Properties
• Drafting Committee: A06.02 - Material Specifications

Relations

• Refers: ASTM A340-23a - Standard Terminology of Symbols and Definitions Relating to Magnetic Testing
• Effective Date: 01-Dec-2023
• Refers: ASTM A340-19b - Standard Terminology of Symbols and Definitions Relating to Magnetic Testing
• Effective Date: 15-Oct-2019
• Refers: ASTM A932/A932M-01(2019) - Standard Test Method for Alternating-Current Magnetic Properties of Amorphous Materials at Power Frequencies Using Wattmeter-Ammeter-Voltmeter Method with Sheet Specimens
• Effective Date: 01-Oct-2019
• Refers: ASTM C693-93(2019) - Standard Test Method for Density of Glass by Buoyancy
• Effective Date: 01-Aug-2019
• Refers: ASTM A340-19a - Standard Terminology of Symbols and Definitions Relating to Magnetic Testing
• Effective Date: 15-Jun-2019
• Refers: ASTM A912/A912M-11(2019) - Standard Test Method for Alternating-Current Magnetic Properties of Amorphous Materials at Power Frequencies Using Wattmeter-Ammeter-Voltmeter Method with Toroidal Specimens
• Effective Date: 01-Apr-2019
• Refers: ASTM A340-19 - Standard Terminology of Symbols and Definitions Relating to Magnetic Testing
• Effective Date: 15-Feb-2019
• Refers: ASTM A340-18 - Standard Terminology of Symbols and Definitions Relating to Magnetic Testing
• Effective Date: 01-Jun-2018
• Refers: ASTM A900/A900M-01(2018) - Standard Test Method for Lamination Factor of Amorphous Magnetic Strip
• Effective Date: 01-May-2018
• Refers: ASTM A340-17a - Standard Terminology of Symbols and Definitions Relating to Magnetic Testing
• Effective Date: 15-Oct-2017
• Refers: ASTM A340-17 - Standard Terminology of Symbols and Definitions Relating to Magnetic Testing
• Effective Date: 01-Jul-2017
• Refers: ASTM A340-16e1 - Standard Terminology of Symbols and Definitions Relating to Magnetic Testing
• Effective Date: 01-May-2016
• Refers: ASTM A340-16 - Standard Terminology of Symbols and Definitions Relating to Magnetic Testing
• Effective Date: 01-May-2016
• Refers: ASTM A340-15 - Standard Terminology of Symbols and Definitions Relating to Magnetic Testing
• Effective Date: 01-Oct-2015
• Refers: ASTM A340-14 - Standard Terminology of Symbols and Definitions Relating to Magnetic Testing
• Effective Date: 01-Oct-2014

Overview

ASTM A901-19 is the standard specification developed by ASTM International for flat-cast, amorphous, semi-processed, iron-based magnetic core alloys. These alloys, recognized for their unique noncrystalline (amorphous) structure, are produced through a rapid-quenching, direct-casting process. Primarily used in commercial power frequency (50 Hz and 60 Hz) applications, these materials are essential for the efficient operation of magnetic devices such as transformer cores. This specification outlines the physical, mechanical, and magnetic property requirements that ensure the consistent performance and reliability of amorphous magnetic core alloys in industrial applications.

Key Topics

• Production Process: Amorphous magnetic core alloys are manufactured via rapid-quenching, resulting in their distinctive noncrystalline structure, which contributes to their superior magnetic characteristics.
• Material Composition: Iron is the principal element, usually alloyed with small amounts of boron and silicon for enhanced magnetic and mechanical properties.
• Property Requirements: The standard details requirements for core loss, permeability, density, ductility, thermal expansion, thermal conductivity, volume resistivity, lamination factor, and surface quality.
• Magnetic Characteristics: The alloys are designed to achieve maximum core-loss values and optimized permeability. These can be further enhanced by heat treatment in a magnetic field, as specified by the end user.
• Quality and Tolerances: Tolerances for strip width and thickness, ductility standards, surface and edge quality, and the presence of pinholes and other imperfections are specified to ensure suitability for transformer-grade applications.
• Testing and Certification: The standard includes mandatory testing and certification requirements for verifying adherence to physical, mechanical, and magnetic property specifications.

Applications

Amorphous magnetic core alloys produced according to ASTM A901-19 offer significant advantages for energy-efficient, high-performance magnetic components such as:

• Power and Distribution Transformers: The reduced core losses make these materials ideal for transformer cores, supporting efficiency improvements in power transmission and distribution.
• Magnetic Components: Used in reactors, inductors, and other devices operating at commercial power frequencies.
• Custom Electrical Applications: Engineers can specify additional magnetic property requirements for specialized uses, tailoring the materials to demanding design and operational environments.

By conforming to ASTM A901-19, manufacturers and users benefit from consistent quality, enhanced energy efficiency, and long-term reliability in their electrical systems.

Related Standards

ASTM A901-19 references and aligns with several related ASTM and international standards, ensuring cohesive quality control and measurement protocols within the energy and materials sectors:

• ASTM A34/A34M - Practice for Sampling and Procurement Testing of Magnetic Materials
• ASTM A340 - Terminology of Symbols and Definitions Relating to Magnetic Testing
• ASTM A370 - Mechanical Testing of Steel Products
• ASTM A664 - Identification of Standard Electrical Steel Grades
• ASTM A700 - Packaging and Shipping of Steel Products
• ASTM A712, A773/A773M, A900/A900M, A912/A912M, A932/A932M - Test methods for various physical and magnetic properties
• IEC 60404-8-11 and IEC 60404-16 - International standards for specifications and measurement of Fe-based amorphous materials

Practical Value

Implementing ASTM A901-19 provides assurance of:

• Consistent and Verifiable Performance: Standardized requirements and testing ensure predictable behavior in critical applications.
• Improved Energy Efficiency: Superior core loss properties translate to lower energy losses, directly impacting operational costs.
• Regulatory and Market Acceptance: Alignment with international standards and trade principles facilitates global trade and market access.
• Quality Assurance: Rigorous quality criteria support procurement, manufacturing, and operational decision-making for electrical equipment manufacturers and users.

By selecting materials in accordance with ASTM A901-19, organizations achieve higher product quality, reliability, and regulatory compliance in their magnetic device applications.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:A901 −19
Standard Specification for
Amorphous Magnetic Core Alloys, Semi-Processed Types
This standard is issued under the fixed designation A901; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This specification covers the general requirements to
ization established in the Decision on Principles for the
which flat-cast, amorphous, semi-processed, iron-base mag-
Development of International Standards, Guides and Recom-
netic core alloys must conform.
mendations issued by the World Trade Organization Technical
1.2 These alloys are produced by a rapid-quenching, direct-
Barriers to Trade (TBT) Committee.
casting process, resulting in metals with noncrystalline (amor-
2. Referenced Documents
phous) structure. The metallic alloys are made to meet speci-
fied maximum core-loss values and are intended primarily for
2.1 ASTM Standards:
commercial power frequency (50- and 60-Hz) applications in
A34/A34M Practice for Sampling and Procurement Testing
magnetic devices. Desirable core-loss and permeability char-
of Magnetic Materials
acteristics are developed by further heat treatment in a mag-
A340 Terminology of Symbols and Definitions Relating to
netic field by the user. The heat treatment typically consists of
Magnetic Testing
heating the material to a temperature of 320 to 420°C in a dry,
A712 Test Method for Electrical Resistivity of Soft Mag-
inert atmosphere for 5 to 10 min, although soak times of up to
netic Alloys
2 h may be used for large transformer cores. A magnetic field
A773/A773M Test Method for Direct Current Magnetic
may be required during annealing as designated by the pro-
Properties of Low Coercivity Magnetic Materials Using
ducer. Exact optimum annealing conditions depend on the
Hysteresigraphs
processing of the material and the size and shape of the device.
A900/A900M Test Method for Lamination Factor of Amor-
phous Magnetic Strip
1.3 Some of these alloys are sensitive to mechanical stress.
A912/A912M Test Method for Alternating-Current Mag-
Care must be exercised in minimizing any stresses on the
netic Properties of Amorphous Materials at Power Fre-
material in its final application, otherwise, its magnetic prop-
quencies Using Wattmeter-Ammeter-Voltmeter Method
erties will be significantly impaired.
with Toroidal Specimens
1.4 This specification is developed to aid in the purchase of
A932/A932M Test Method for Alternating-Current Mag-
transformer grade amorphous strip. It provides the chemical,
netic Properties of Amorphous Materials at Power Fre-
physical, and magnetic parameters and procedures for quality
quencies Using Wattmeter-Ammeter-Voltmeter Method
control tests.
with Sheet Specimens
1.5 The values stated in SI units are to be regarded as
C693 Test Method for Density of Glass by Buoyancy
standard. The values given in parentheses are numerical
D3455 Test Methods for Compatibility of Construction Ma-
conversionstocustomary(cgsandinch-pound)unitswhichare
terial with Electrical Insulating Oil of Petroleum Origin
provided for information only and are not considered standard.
3. Terminology
1.6 This standard does not purport to address the safety
3.1 The terms and symbols used in this specification are
concerns associated with its use. It is the responsibility of the
defined in Terminology A340.
user of this standard to establish appropriate safety, health,
andenvironmentalpracticesanddeterminetheapplicabilityof
4. Classification
regulatory limitations prior to use.
4.1 The classification of iron-based amorphous alloys con-
forming to this material specification are given in Table 1 and
Table 2.
This specification is under the jurisdiction of ASTM Committee A06 on
Magnetic Properties and is the direct responsibility of Subcommittee A06.02 on
Material Specifications. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Aug. 1, 2019. Published August 2019. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1990. Last previous edition approved in 2012 as A901 – 12. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/A0901-19. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A901−19
4.2 The material name in Table 1 and Table 2 comprises the agreed upon between the user and the producer. Alternatively,
following in the order given. the nominal thickness may be determined by Eq 1:
4.2.1 The letter AM for amorphous magnetic material,
d 5 m⁄ρ ·b·l (1)
m
4.2.2 The two-digit number following AM indicating one
where:
hundredtimesthespecificvalueofmaximumspecificcoreloss
d = average calculated thickness of the test specimen in
at 1.3 T (13 000 G) magnetic flux density level at 60 Hz in
watts per kilogram (watts per pound), metres,
m = mass of the specimen in kilograms,
4.2.3 The two-digit number following maximum specific
b = width of the specimen in metres,
core loss designation indicating one thousand times the nomi-
l = length of the specimen in metres, and
nal thickness of the strip in millimetres,
ρ = conventional density of the specimen in kilogram per
m
4.2.4 The alphabet letters, S and P, following strip thickness
cubic metre.
for conventional and high permeability grade, respectively,
4.2.5 The single digit number following grade designation
7. Material Requirements
being one-tenth of the measuring frequency, and
4.2.6 The last two-digit number indicating one-hundred
7.1 Amorphous magnetic core alloys are composed princi-
times the specified value of the minimum lamination factor.
pally of iron with small amounts of alloying elements such as
boron and silicon. Other chemical elements are in residual
5. Ordering Information
amounts or can be added to improve fabrication or the physical
5.1 Order for materials conforming to the specification shall
ormagneticproperties.Thechemistryislefttothediscretionof
indicate the following information: the producer. The producer shall provide, on request, a state-
5.1.1 Reference to this specification and year of issue
ment of the nominal chemistry being supplied.
revision.
5.1.2 Reference to material name. 8. Sampling
5.1.3 Depending upon the desired end use, other magnetic
8.1 Acontinuously cast strip in one coil without breaks will
properties such as specific exciting power, saturation magnetic
constitute one test lot. In practice, this may represent quantities
flux density, residual flux density and coercive field strength
up to 1000 kg (2200 lb), depending on the width of the strip.
mayneedtobespecified.Theuserisresponsibleforspecifying
8.2 Test samples normally shall be taken from both ends of
the limits on magnetic properties. The user also states whether
the continuous strip of each test lot. Other sample frequencies
and what specific tests are required.
may be used as agreed upon by the producer and the user.
6. Dimensions
8.3 For small coils, less than 45 kg (100 lb), and for coils
6.1 Width—Tolerances on nominal as-cast strip width shall containing splices, the test lot shall be as agreed upon between
be 60.65 % of the specified purchase width. the producer and the user.
6.2 Thickness—The nominal thickness shall be 0.025 mm
9. Physical and Mechanical Property Requirements
(0.001 in.) as measured by a 6.35 mm (0.25-in.) diameter anvil
micrometer. The nominal thickness may vary 60.005 mm 9.1 Density—The density shall be provided by the producer
3 3
(60.0002 in.), but the maximum thickness variation across the to a precision of 650 kg/m (60.05 g/cm ) as measured by
width shall be within 610 % of the mean thickness, or as Test Method C693.
TABLE 1 Magnetic and Physical Properties of the Conventional Grades of Fe-based Amorphous Strip
Minimum
Maximum Specific Core Loss at Maximum Specific Core Loss at
Nominal Magnetic Flux Minimum
1.3 T (13 000 G) 1.4 T (14 000 G)
Material Name Thickness Density B at H = Lamination
W/kg (W/lb) W/kg (W/lb)
80 A/m (1.0 Oe) Factor
mm (in.) 50 Hz 60 Hz 50 Hz 60 Hz T (G)
AM11-25S6-90 0.90
AM11-25S6-88 0.88
0.025 (0.001) 0.08 (0.036) 0.11 (0.050) 0.11 (0.050) 0.14 (0.064) 1.35 (13 500)
AM11-25S6-86 0.86
AM11-25S6-84 0.84
AM13-25S6-90 0.90
AM13-25S6-88 0.88
0.025 (0.01) 0.10 (0.045) 0.13 (0.059) 0.13 (0.059) 0.17 (0.077) 1.35 (13 500)
AM13-25S6-86 0.86
AM13-25S6-84 0.84
AM15-25S6-90 0.90
AM15-25S6-88 0.88
0.025 (0.001) 0.12 (0.055) 0.15 (0.068) 0.16 (0.073) 0.20 (0.091) 1.35 (13 500)
AM15-25S6-86 0.86
AM15-25S6-84 0.84
A901−19
TABLE 2 Magnetic and Physical Properties of the High Permeability Grades of Fe-based Amorphous Strip
Minimum
Maximum Specific Core Loss at Maximum Specific Core Loss at
Nominal Magnetic Flux Minimum
1.3 T (13 000 G) 1.4 T (14 000 G)
Material Name Thickness Density B at H = Lamination
W/kg (W/lb) W/kg (W/lb)
80 A/m (1.0 Oe) Factor
mm (in.) 50 Hz 60 Hz 50 Hz 60 Hz T (G)
AM11-25P6-90 0.90
AM11-25P6-88 0.88
0.025 (0.001) 0.08 (0.036) 0.11 (0.050) 0.11 (0.050) 0.14 (0.064) 1.50 (15 000)
AM11-25P6-86 0.86
AM11-25P6-84 0.84
AM13-25P6-90 0.90
AM13-25P6-88 0.88
0.025 (0.01) 0.10 (0.045) 0.13 (0.059) 0.13 (0.059) 0.17 (0.077) 1.50 (15 000)
AM13-25P6-86 0.86
AM13-25P6-84 0.84
AM15-25P6-90 0.90
AM15-25P6-88 0.88
0.025 (0.001) 0.12 (0.055) 0.15 (0.068) 0.16 (0.073) 0.20 (0.091) 1.50 (15 000)
AM15-25P6-86 0.86
AM15-25P6-84 0.84
9.2 Ductility—Strip bend ductility, with free solidification formmaybeusedasagreeduponbetweentheproducerandthe
surface facing inward, shall be such that a minimum 1-m (39.4 user. See 1.2 for an example of typical heat treatment condi-
in.) length of ribbon may be passed 180° around a 3-mm tions. Demagnetizing factor should be considered when a
(0.125-in.) polished steel rod without cracking or fracture. magnetic field is applied to a flat strip for magnetic field
Alternativel
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: A901 − 12 A901 − 19
Standard Specification for
Amorphous Magnetic Core Alloys, Semi-Processed Types
This standard is issued under the fixed designation A901; 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 (´) indicates an editorial change since the last revision or reapproval.
1. 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 noncrystalline (amorphous)
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 user. 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, although soak times of up to 2 h may be used for
large transformer cores. A magnetic field may be required during annealing as designated by the producer. Exact optimum
annealing conditions depend on the processing of the material and the size and shape of the device.
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 significantly impaired.
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.
1.5 The values stated in customary (cgs-emu and inch-pound) SI units are to be regarded as standard. The values given in
parentheses are mathematicalnumerical conversions to SI customary (cgs and inch-pound) units which are provided for
information only and are not considered standard.
NOTE 1—For more information on procedures associated with this specification, refer to the following: Practices A34/A34M, A664, A700, and B490;
Test Methods A370 and A773/A773M.
1.6 This standard does not purport to address the safety concerns associated with its use. It is the responsibility of the user of
this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the applicability of
regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
A34/A34M Practice for Sampling and Procurement Testing of Magnetic Materials
A340 Terminology of Symbols and Definitions Relating to Magnetic Testing
A370 Test Methods and Definitions for Mechanical Testing of Steel Products
A664 Practice for Identification of Standard Electrical Steel Grades in ASTM Specifications
A700 Guide for Packaging, Marking, and Loading Methods for Steel Products for Shipment
A712 Test Method for Electrical Resistivity of Soft Magnetic Alloys
A773/A773M Test Method for Direct Current Magnetic Properties of Low Coercivity Magnetic Materials Using Hysteresig-
raphs
This specification is under the jurisdiction of ASTM Committee A06 on Magnetic Properties and is the direct responsibility of Subcommittee A06.02 on Material
Specifications.
Current edition approved Feb. 15, 2012Aug. 1, 2019. Published March 2012August 2019. Originally approved in 1990. Last previous edition approved in 20082012 as
A901–03(2008).A901 – 12. DOI: 10.1520/A0901-12.10.1520/A0901-19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A901 − 19
A900/A900M Test Method for Lamination Factor of Amorphous Magnetic Strip
A912/A912M Test Method for Alternating-Current Magnetic Properties of Amorphous Materials at Power Frequencies Using
Wattmeter-Ammeter-Voltmeter Method with Toroidal Specimens
B490A932/A932M Practice for Micrometer Bend Test for Ductility of ElectrodepositsTest Method for Alternating-Current
Magnetic Properties of Amorphous Materials at Power Frequencies Using Wattmeter-Ammeter-Voltmeter Method with Sheet
Specimens
C693 Test Method for Density of Glass by Buoyancy
D3455 Test Methods for Compatibility of Construction Material with Electrical Insulating Oil of Petroleum Origin
3. Terminology
3.1 The terms and symbols used in this specification are defined in Terminology A340.
4. Classification
4.1 The classification of iron-based amorphous alloys conforming to this material specification are given in Table 1 and Table
2.
4.2 The material name in Table 1 and Table 2 comprises the following in the order given.
4.2.1 The letter AM for amorphous magnetic material,
4.2.2 The two-digit number following AM indicating one hundred times the specific value of maximum specific core loss at 1.3
T (13 000 G) magnetic flux density level at 60 Hz in watts per kilogram (watts per pound),
4.2.3 The two-digit number following maximum specific core loss designation indicating one thousand times the nominal
thickness of the strip in millimetres,
4.2.4 The alphabet letters, S and P, following strip thickness for conventional and high permeability grade, respectively,
4.2.5 The single digit number following grade designation being one-tenth of the measuring frequency, and
4.2.6 The last two-digit number indicating one-hundred times the specified value of the minimum lamination factor.
5. Ordering Information
5.1 Order for materials conforming to the specification shall indicate the following information:
5.1.1 Reference to this specification and year of issue revision.
5.1.2 Reference to material name.
5.1.3 Depending upon the desired end use, other magnetic properties such as specific exciting power, saturation magnetic flux
density, residual flux density and coercive field strength may need to be specified. The user is responsible for specifying the limits
on magnetic properties. The user also states whether and what specific tests are required.
6. Dimensions
6.1 Width—Tolerances on nominal as-cast strip width shall be 60.65%60.65 % of the specified purchase width.
6.2 Thickness—The nominal thickness shall be 0.001 in. (0.025 mm)0.025 mm (0.001 in.) as measured by a 0.25-in. (6.35-mm)
6.35 mm (0.25-in.) diameter anvil micrometer. The nominal thickness may vary 60.0002 in. (60.005 mm),60.005 mm (60.0002
in.), but the maximum thickness variation across the width shall be within 610 % of the mean thickness, or as agreed upon
between the user and the producer. Alternatively, the nominal thickness may be determined by Eq 1:
d 5 m⁄ρ ·b·l (1)
m
where:
d = average calculated thickness of the test specimen in metres,
m = mass of the specimen in kilograms,
b = width of the specimen in metres,
l = length of the specimen in metres, and
ρ = conventional density of the specimen in kilogram per cubic metre.
m
7. Material Requirements
7.1 Amorphous magnetic core alloys are composed principally of iron with small amounts of alloying elements such as boron
and silicon. Other chemical elements are in residual amounts or can be added to improve fabrication or the physical or magnetic
properties. The chemistry is left to the discretion of the producer. The producer shall provide, on request, a statement of the nominal
chemistry being supplied. The nominal composition for one particular alloy, in weight percent, is: iron 92.3, silicon 5.2, and boron
2.5.
8. Sampling
8.1 A continuously cast strip in one coil without breaks will constitute one test lot. In practice, this may represent quantities up
to 2200 lb (1000 kg),1000 kg (2200 lb), depending on the width of the strip.
A901 − 19
8.2 Test samples normally shall be taken from both ends of the continuous strip of each test lot. Other sample frequencies may
be used as agreed upon by the producer and the user.
8.3 For small coils, less than 100 lb (45 kg),45 kg (100 lb), and for coils containing splices, the test lot shall be as agreed upon
between the producer and the user.
9. Physical and Mechanical Property Requirements
3 3
9.1 Density—The density shall be provided by the producer to a precision of 60.05 g/cm650 kg/m (650 kg/m(60.05 g/cm )
as measured by Test Method C693.
TABLE 1 Magnetic and Physical Properties of the Conventional Grades of Fe-based Amorphous Strip
Minimum
Maximum Specific Core Loss at Maximum Specific Core Loss at
Nominal Magnetic Flux Minimum
1.3 T (13 000 G) 1.4 T (14 000 G)
Material Name Thickness Density B at H = Lamination
W/kg (W/lb) W/kg (W/lb)
80 A/m (1.0 Oe) Factor
mm (in.) 50 Hz 60 Hz 50 Hz 60 Hz T (G)
AM11-25S6-90 0.90
AM11-25S6-88 0.88
0.025 (0.001) 0.08 (0.036) 0.11 (0.050) 0.11 (0.050) 0.14 (0.064) 1.35 (13 500)
AM11-25S6-86 0.86
AM11-25S6-84 0.84
AM13-25S6-90 0.90
AM13-25S6-88 0.88
0.025 (0.01) 0.10 (0.045) 0.13 (0.059) 0.13 (0.059) 0.17 (0.077) 1.35 (13 500)
AM13-25S6-86 0.86
AM13-25S6-84 0.84
AM15-25S6-90 0.90
AM15-25S6-88 0.88
0.025 (0.001) 0.12 (0.055) 0.15 (0.068) 0.16 (0.073) 0.20 (0.091) 1.35 (13 500)
AM15-25S6-86 0.86
AM15-25S6-84 0.84
TABLE 2 Magnetic and Physical Properties of the High Permeability Grades of Fe-based Amorphous Strip
Minimum
Maximum Specific Core Loss at Maximum Specific Core Loss at
Nominal Magnetic Flux Minimum
1.3 T (13 000 G) 1.4 T (14 000 G)
Material Name Thickness Density B at H = Lamination
W/kg (W/lb) W/kg (W/lb)
80 A/m (1.0 Oe) Factor
mm (in.) 50 Hz 60 Hz 50 Hz 60 Hz T (G)
AM11-25P6-90 0.90
AM11-25P6-88 0.88
0.025 (0.001) 0.08 (0.036) 0.11 (0.050) 0.11 (0.050) 0.14 (0.064) 1.50 (15 000)
AM11-25P6-86 0.86
AM11-25P6-84 0.84
AM13-25P6-90 0.90
AM13-25P6-88 0.88
0.025 (0.01) 0.10 (0.045) 0.13 (0.059) 0.13 (0.059) 0.17 (0.077) 1.50 (15 000)
AM13-25P6-86 0.86
AM13-25P6-84 0.84
AM15-25P6-90 0.90
AM15-25P6-88 0.88
0.025 (0.001) 0.12 (0.055) 0.15 (0.068) 0.16 (0.073) 0.20 (0.091) 1.50 (15 000)
AM15-25P6-86 0.86
AM15-25P6-84 0.84
9.2 Ductility—Strip bend ductility, with free solidification surface facing inward, shall be such that a minimum 1-m (39.4 in.)
length of ribbon may be passed 180° around a 0.125-in. (3-mm)3-mm (0.125-in.) polished steel rod without cracking or fracture.
Alternatively, the acceptable number of brittle spots shall be determined by agreement between the producer and the user. Further
information is found in Appendix X3.
9.3 Thermal Expansion—The nominal coefficient of thermal expansion shall be reported for the temperature range 40 to 400°C.
400°C (104 o 752°F).
9.4 Thermal Conductivity—The average value measured across the width shall be reported for temperatures of 25, 100, and
400°C. 400°C (77, 212, and 572°F). These values of thermal conductivity of the material shall not differ from the published values
by more than 20 %.
9.5 Electrical Resistivity—The electrical resistivity shall be reported as measured by Test Method A712.
9.6 Lamination Factor—The minimum lamination factor of as–cast material shall be 81.5 % as each grade of as-cast material
measured in accordance with Test Method
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