ASTM A811-15(2022)
(Specification)Standard Specification for Soft Magnetic Iron Parts Fabricated by Powder Metallurgy Techniques
Standard Specification for Soft Magnetic Iron Parts Fabricated by Powder Metallurgy Techniques
ABSTRACT
This specification covers soft magnetic iron parts fabricated by pressing and sintering of iron powder. The specification does not cover parts produced by metal injection molding. Parts produced to this specification shall have a minimum sintered density of 6.6 g/cm3 (6600 kg/m3) in the magnetically critical section of the part. Chemical requirements for the sintered part are given. Three grades distinguished by the measured maximum value of coercive field strength are defined. Apart from the required measurements of sintered density, chemical composition and coercive field strength, information on magnetic aging and its detection is given. Appendices containing magnetic and mechanical property data for a variety of sintering conditions are provided.
SCOPE
1.1 This specification covers parts produced from iron powder metallurgy materials.
1.2 This specification deals with powder metallurgy parts in the sintered or annealed condition. Should the sintered parts be subjected to any secondary operation that causes mechanical strain, such as machining or sizing, they should be resintered or annealed.
1.3 The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to customary (cgs-emu and inch-pound) units, which are provided for information only, and are not considered standard.
1.4 This standard does not purport to address all of the safety concerns, if any, 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.
1.5 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
Relations
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:A811 −15 (Reapproved 2022)
Standard Specification for
Soft Magnetic Iron Parts Fabricated by Powder Metallurgy
Techniques
This standard is issued under the fixed designation A811; 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 A596/A596M Test Method for Direct-Current Magnetic
PropertiesofMaterialsUsingthePointbyPoint(Ballistic)
1.1 This specification covers parts produced from iron
Method and Ring Specimens
powder metallurgy materials.
A773/A773M Test Method for Direct Current Magnetic
1.2 This specification deals with powder metallurgy parts in
Properties of Low Coercivity Magnetic Materials Using
the sintered or annealed condition. Should the sintered parts be
Hysteresigraphs
subjected to any secondary operation that causes mechanical
B962 Test Methods for Density of Compacted or Sintered
strain,suchasmachiningorsizing,theyshouldberesinteredor
Powder Metallurgy (PM) Products Using Archimedes’
annealed.
Principle
E1019 Test Methods for Determination of Carbon, Sulfur,
1.3 The values stated in SI units are to be regarded as
standard. The values given in parentheses are mathematical Nitrogen, and Oxygen in Steel, Iron, Nickel, and Cobalt
Alloys by Various Combustion and Inert Gas Fusion
conversions to customary (cgs-emu and inch-pound) units,
which are provided for information only, and are not consid- Techniques
ered standard.
3. Terminology
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 3.1 The terms and symbols used in this specification are
responsibility of the user of this standard to establish appro- defined in Terminology A340.
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use. 4. Ordering Information
1.5 This international standard was developed in accor-
4.1 Purchase orders for parts conforming to this specifica-
dance with internationally recognized principles on standard-
tion shall include the following information:
ization established in the Decision on Principles for the
4.1.1 Reference to this specification and year of issue/
Development of International Standards, Guides and Recom-
revision,
mendations issued by the World Trade Organization Technical
4.1.2 Reference to an applicable part drawing,
Barriers to Trade (TBT) Committee.
4.1.3 Quantity required,
4.1.4 Acritical cross section of the part shall be defined and
2. Referenced Documents
so indicated on the applicable part drawing.The location of the
2.1 ASTM Standards: critical section is by mutual agreement between the user and
the producer (6.2),
A34/A34M Practice for Sampling and Procurement Testing
of Magnetic Materials 4.1.5 Magnetic property requirements if they are other than
stated in Table 1,
A340 Terminology of Symbols and Definitions Relating to
Magnetic Testing 4.1.6 Whethercertificationofchemicalanalysisormagnetic
property evaluation is required (Sections 5 and 7),
4.1.7 Marking and packaging requirements (Section 12),
and
This specification is under the jurisdiction of ASTM Committee A06 on
Magnetic Properties and is the direct responsibility of Subcommittee A06.02 on 4.1.8 Exceptions to this specification or special require-
Material Specifications.
ments such as functional testing as mutually agreed upon
Current edition approved Oct. 1, 2022. Published November 2022. Originally
between the producer and the user.
approved in 1983. Last previous edition approved in 2015 as A811 – 15. DOI:
10.1520/A0811-15R22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 5. Chemical Composition
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.1 The chemical composition of the parts shall conform to
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the requirements prescribed in Table 2.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A811−15 (2022)
TABLE 1 Maximum Coercive Field Strength Requirements
7.5 Coercive Field Strength Requirements—Three grades,
Grade Coercive Field Strength defined by coercive field strength, are stipulated by this
1 140 A/m (1.8 Oe) specification and are listed in Table 1. The coercive field
2 160 A/m (2.0 Oe)
strength requirement for Grade 3 was developed from an
3 180 A/m (2.3 Oe)
interlaboratory study. The values for Grades 1 and 2 are based
on a literature review and are believed to reflect the current
industry capabilities.
TABLE 2 Chemical Requirements (weight percent)
Element % 7.6 Magnetic Aging—Nitrogen introduced during sintering
can cause time-dependent degradation of magnetic properties.
Carbon, max 0.03
Oxygen, max 0.10
Therefore, when requested by the user, the producer shall test
Nitrogen, max 0.01
for aging. To determine the susceptibility of the parts to aging,
A
Others 0.50, max
B
Iron balance thetestring(s)shouldbeheatedinairforeither100 hat150 °C
A
6 5 °C or 600 h at 100 °C 6 5 °C and the coercive field
Others refers to trace elements which are to be regarded as incidental and not
deliberate additions.
strength remeasured. A change in coercive field strength of
B
Iron is the balance by difference. Quantitative analysis of this element is not
10 % or more of the original value is evidence that aging has
required.
occurred.
7.7 Since magnetic properties are strongly affected by
processconditions,refertoAppendixX1fortypicalvaluesand
explanatory notes.
5.2 Determination of metallic constituents shall be by a
method acceptable to both the producer and the user. Analysis
8. Workmanship, Finish, and Appearance
of carbon, oxygen, sulfur, and nitrogen shall be done in
8.1 The parts shall be uniform in composition and uniform
accordance with Test Methods E1019.
in density within critical sections.
6. Sintered Density Requirements 8.2 If parts are sectioned or fractured, there shall be no
readily recognizable defects.
6.1 Magnetic and residual induction of powder metallurgy
parts strongly depend on density. The density of powder
9. Sampling
metallurgy parts is determined by the compressibility of the
powder, the compacting pressure, and sintering practice
9.1 A lot shall consist of parts of the same form and
(temperature, time, and atmosphere).
dimensions, produced from a single mixed powder batch and
from an unchanged process, without d
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