ASTM A904-20

Standard Specification for 50 Nickel-50 Iron Powder Metallurgy Soft Magnetic Parts

ABSTRACT
This specification covers the magnetic property requirements of 50 nickel-50 iron soft magnetic parts fabricated by powder metallurgy techniques in the sintered or annealed conditions, intended for parts that require high magnetic permeability, high electrical resistivity, low coercive field strength, and low hysteresis loss. This specification does not cover parts produced by metal injection molding. Parts shall be tested and adhere to the chemical composition, sintered density and coercive field strength requirements listed in this specification. Appendices contain information on typical magnetic properties and heat treatment.
SCOPE
1.1 This specification covers the magnetic properties of 50 nickel-50 iron parts fabricated by powder metallurgy techniques and is intended for parts that require high magnetic permeability, high electrical resistivity, low coercive field strength, and low hysteresis loss. It differs from the wrought alloy specification (see Specification A753) because these parts are porous. A number of magnetic properties such as permeability are proportional to the sintered density.  
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.  
1.3.1 There are selected values presented in two units, both of which are in acceptable SI units. These are differentiated by the word “or,” as in “μΩ-cm, or, Ω-m.”  
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

• Status: Published
• Publication Date: 31-May-2020
• ICS: 77.160 - Powder metallurgy
• Technical Committee: A06 - Magnetic Properties
• Drafting Committee: A06.02 - Material Specifications

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:A904 −20
Standard Specification for
1
50 Nickel-50 Iron Powder Metallurgy Soft Magnetic Parts
This standard is issued under the fixed designation A904; 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 2. Referenced Documents
2
1.1 This specification covers the magnetic properties of 50 2.1 ASTM Standards:
nickel-50 iron parts fabricated by powder metallurgy tech- A34/A34M Practice for Sampling and Procurement Testing
niques and is intended for parts that require high magnetic of Magnetic Materials
permeability, high electrical resistivity, low coercive field A340 Terminology of Symbols and Definitions Relating to
strength, and low hysteresis loss. It differs from the wrought Magnetic Testing
alloyspecification(seeSpecificationA753)becausetheseparts A596/A596M Test Method for Direct-Current Magnetic
are porous. A number of magnetic properties such as perme- Properties of Materials Using the Ballistic Method and
ability are proportional to the sintered density. Ring Specimens
A753 Specification for Wrought Nickel-Iron Soft Magnetic
1.2 This specification deals with powder metallurgy parts in
Alloys (UNS K94490, K94840, N14076, N14080)
the sintered or annealed condition. Should the sintered parts be
A773/A773M Test Method for Direct Current Magnetic
subjected to any secondary operation that causes mechanical
Properties of Low Coercivity Magnetic Materials Using
strain,suchasmachiningorsizing,theyshouldberesinteredor
Hysteresigraphs
annealed.
B962 Test Methods for Density of Compacted or Sintered
1.3 The values stated in SI units are to be regarded as
Powder Metallurgy (PM) Products Using Archimedes’
standard. The values given in parentheses are mathematical
Principle
conversions to customary (cgs-emu and inch-pound) units,
E1019 Test Methods for Determination of Carbon, Sulfur,
whichareprovidedforinformationonlyandarenotconsidered
Nitrogen, and Oxygen in Steel, Iron, Nickel, and Cobalt
standard.
Alloys by Various Combustion and Inert Gas Fusion
1.3.1 There are selected values presented in two units, both
Techniques
of which are in acceptable SI units. These are differentiated by
the word “or,” as in “µΩ-cm, or,Ω-m.” 3. Terminology
1.4 This standard does not purport to address all of the
3.1 The terms and symbols used in this specification are
safety concerns, if any, associated with its use. It is the
defined in Terminology A340.
responsibility of the user of this standard to establish appro-
4. Ordering Information
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
4.1 Orders for parts conforming to this specification shall
1.5 This international standard was developed in accor-
include the following information.
dance with internationally recognized principles on standard-
4.1.1 Reference to this standard and year of issue/revision.
ization established in the Decision on Principles for the
4.1.2 Reference to an applicable part drawing.
Development of International Standards, Guides and Recom-
4.1.3 Quantity required.
mendations issued by the World Trade Organization Technical
4.1.4 Acritical cross section of the part shall be defined and
Barriers to Trade (TBT) Committee.
so indicated on the applicable part drawing.The location of the
critical section is by mutual agreement between the user and
producer (see 6.2).
1
This specification is under the jurisdiction of ASTM Committee A06 on
Magnetic Properties and is the direct responsibility of Subcommittee A06.02 on
2
Material Specifications. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
CurrenteditionapprovedJune1,2020.PublishedJuly2020.Originallyapproved contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
in 1990. Last previous edition approved in 2014 as A904 – 14. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
A0904-20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
A904−20
4.1.5 Magnetic property requirements if they are other than 7.4 For the purpose of this specification, only the coercive
stated in 7.5. field strength determined from a maximum applied magnetic
4.1.6 Certification of chemical composition or magnetic field strength of 1200 A/m (15 Oe) needs to be determined.
proper
...

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: A904 − 14 A904 − 20
Standard Specification for
1
50 Nickel-50 Iron Powder Metallurgy Soft Magnetic Parts
This standard is issued under the fixed designation A904; 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 magnetic properties of 50 nickel-50 iron parts fabricated by powder metallurgy techniques and
is intended for parts that require high magnetic permeability, high electrical resistivity, low coercive field strength, and low
hysteresis loss. It differs from the wrought alloy specification (see Specification A753) because these parts are porous. A number
of magnetic properties such as permeability are proportional to the sintered density.
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 customary (cgs-emu and inch-pound) SI units are to be regarded separately as standard. The values
given in parentheses are mathematical conversions to SI customary (cgs-emu and inch-pound) units, which are provided for
information only and are not considered standard.
1.3.1 There are selected values presented in two units, both of which are in acceptable SI units. These are differentiated by the
word “or,” as in “μΩ-cm, or, Ω-m.”
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 safety, health, and healthenvironmental 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.
2. Referenced Documents
2
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
A596/A596M Test Method for Direct-Current Magnetic Properties of Materials Using the Ballistic Method and Ring Specimens
A753 Specification for Wrought Nickel-Iron Soft Magnetic Alloys (UNS K94490, K94840, N14076, N14080)
A773/A773M Test Method for Direct Current Magnetic Properties of Low Coercivity Magnetic Materials Using Hysteresig-
raphs
B328 Test Method for Density, Oil Content, and Interconnected Porosity of Sintered Metal Structural Parts and Oil-Impregnated
3
Bearings (Withdrawn 2009)
B962 Test Methods for Density of Compacted or Sintered Powder Metallurgy (PM) Products Using Archimedes’ Principle
E1019 Test Methods for Determination of Carbon, Sulfur, Nitrogen, and Oxygen in Steel, Iron, Nickel, and Cobalt Alloys by
Various Combustion and Inert Gas Fusion Techniques
3. Terminology
3.1 The terms and symbols used in this specification are defined in Terminology A340.
1
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 May 1, 2014June 1, 2020. Published May 2014July 2020. Originally approved in 1990. Last previous edition approved in 20092014 as
A904A904 – 14.–09. DOI: 10.1520/A0904-14.10.1520/A0904-20.
2
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
1

---------------------- Page: 1 ----------------------
A904 − 20
4. Ordering Information
4.1 Orders for parts conforming to this specification shall include the following information.
4.1.1 Reference to this standard and year of issue/revision.
4.1.2 Reference to an applicable part drawing.
4.1.3 Quantity required.
4.1.4 A critical cross section of the part shall be defined and so indicated on the applicable
...