ASTM A838-18
(Specification)Standard Specification for Free-Machining Ferritic Stainless Soft Magnetic Alloy Bar for Relay Applications
Standard Specification for Free-Machining Ferritic Stainless Soft Magnetic Alloy Bar for Relay Applications
ABSTRACT
This specification covers nominally 17.5% Cr free-machining ferritic stainless soft magnetic alloy produced or supplied expressly in cold-finished bar form for use in magnetic cores and other parts requiring a corrosion-resistant, high permeability, low-coercivity steel. This specification does not cover either cast parts or parts produced by powder metallurgy techniques. Two specific alloy types are covered distinguished by different silicon levels. Required measurements include chemical analysis and dc magnetic property measurement. The magnetic properties depend both on the grade and the dimensions. Apart from the requirements, the specification contains useful appendices discussing the magnetic testing of these alloys and typical magnetic and physical properties.
SCOPE
1.1 This specification covers free-machining ferritic stainless soft magnetic alloy produced or supplied expressly in cold-finished bar form for use in magnetic cores and other parts requiring a high permeability, low-coercivity stainless steel.
1.1.1 This specification does not cover either cast parts or parts produced by powder metallurgy techniques.
1.2 Two specific alloy types are covered. The primary constituents are shown in Table 1. These types have corrosion resistance similar to AISI Type 430F and Type 430F, Specification A582/A582M.
1.3 This specification covers only these alloy types supplied in cold-finished bars in cross-sectional shapes such as rounds, squares, hexagons, and octagons with diameters (diagonals) greater than or equal to 6.35 mm (0.250 in.) and less than or equal to 41.5 mm (1.63 in.).2
1.4 Certain cold-finished round bar products are capable of being supplied mill annealed to required magnetic properties such as low coercivity. The size range that can be mill annealed is from 6.35 to 41.5 mm (0.250 to 1.63 in.). Other products of these alloys cannot be mill annealed to produce equivalently low coercivity; hence, the final machined parts should be heat treated as recommended by the producer.
1.5 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.
1.6 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.
1.7 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.
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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:A838 −18
Standard Specification for
Free-Machining Ferritic Stainless Soft Magnetic Alloy Bar
1
for Relay Applications
This standard is issued under the fixed designation A838; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.1 This specification covers free-machining ferritic stain-
1.7 This international standard was developed in accor-
less soft magnetic alloy produced or supplied expressly in
dance with internationally recognized principles on standard-
cold-finishedbarformforuseinmagneticcoresandotherparts
ization established in the Decision on Principles for the
requiring a high permeability, low-coercivity stainless steel.
Development of International Standards, Guides and Recom-
1.1.1 This specification does not cover either cast parts or
mendations issued by the World Trade Organization Technical
parts produced by powder metallurgy techniques.
Barriers to Trade (TBT) Committee.
1.2 Two specific alloy types are covered. The primary
constituents are shown in Table 1. These types have corrosion
2. Referenced Documents
resistance similar to AISI Type 430F and Type 430F, Specifi-
3
cation A582/A582M.
2.1 ASTM Standards:
A34/A34MPractice for Sampling and Procurement Testing
1.3 Thisspecificationcoversonlythesealloytypessupplied
of Magnetic Materials
in cold-finished bars in cross-sectional shapes such as rounds,
A340Terminology of Symbols and Definitions Relating to
squares, hexagons, and octagons with diameters (diagonals)
Magnetic Testing
greater than or equal to 6.35 mm (0.250 in.) and less than or
2
A341/A341MTest Method for Direct Current Magnetic
equal to 41.5 mm (1.63 in.).
Properties of Soft Magnetic Materials Using D-C Per-
1.4 Certain cold-finished round bar products are capable of
meametersandthePointbyPoint(Ballistic)TestMethods
being supplied mill annealed to required magnetic properties
A582/A582MSpecification for Free-Machining Stainless
suchaslowcoercivity.Thesizerangethatcanbemillannealed
Steel Bars
is from 6.35 to 41.5 mm (0.250 to 1.63 in.). Other products of
A596/A596MTest Method for Direct-Current Magnetic
these alloys cannot be mill annealed to produce equivalently
Properties of Materials Using the Ballistic Method and
low coercivity; hence, the final machined parts should be heat
Ring Specimens
treated as recommended by the producer.
A773/A773MTest Method for Direct Current Magnetic
1.5 The values stated in SI units are to be regarded as
Properties of Low Coercivity Magnetic Materials Using
standard. The values given in parentheses are mathematical
Hysteresigraphs
conversions to customary (cgs-emu and inch-pound) units
E1019Test 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
Techniques
1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
2.2 Other Standard:
responsibility of the user of this standard to establish appro-
IEC Publication 60404-7Methods of Measurement of the
Coercivity of Magnetic Materials in an Open Magnetic
4
Circuit
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.
3
Current edition approved Oct. 1, 2018. Published October 2018. Originally For referenced ASTM standards, visit the ASTM website, www.astm.org, or
approved in 1985. Last previous edition approved in 2013 as A838–02 (2013). contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
DOI: 10.1520/A0838-18. Standards volume information, refer to the standard’s Document Summary page on
2
Other product forms can be supplied to the chemistries listed in this specifi- the ASTM website.
4
cation; however, all other requirements shall be subject to negotiation between the Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
producer and the user. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1
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A838−18
TABLE 1 Alloy Types TABLE 3 Grades for Alloy Type 2
Nomi
...
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: A838 − 02 (Reapproved 2013) A838 − 18
Standard Specification for
Free-Machining Ferritic Stainless Soft Magnetic Alloy Bar
1
for Relay Applications
This standard is issued under the fixed designation A838; 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 free-machining ferritic stainless soft magnetic alloy produced or supplied expressly in
cold-finished bar form for use in magnetic cores and other parts requiring a high permeability, low-coercivity stainless steel.
1.1.1 This specification does not cover either cast parts or parts produced by powder metallurgy techniques.
1.2 Two specific alloy types are covered. The primary constituents are shown in Table 1. These types have corrosion resistance
similar to AISI Type 430F and Type 430F, Specification A582/A582M.
1.3 This specification covers only these alloy types supplied in cold-finished bars in cross-sectional shapes such as rounds,
squares, hexagons, and octagons with diameters (diagonals) greater than or equal to 0.250 in. (6.35 mm)6.35 mm (0.250 in.) and
2
less than or equal to 1.625 in. (41.28 mm).41.5 mm (1.63 in.).
1.4 Certain cold-finished round bar products are capable of being supplied mill annealed to required magnetic properties such
as low coercivity. The size range that can be mill annealed is from 0.250 to 1.625 in. (6.35 to 41.28 mm).6.35 to 41.5 mm (0.250
to 1.63 in.). Other products of these alloys cannot be mill annealed to produce equivalently low coercivity; hence, the final
machined parts should be heat treated as recommended by the producer.
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 mathematical conversions to SI customary (cgs-emu and inch-pound) units which are provided for information
only and are not considered standard.
1.6 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.
1.7 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
3
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
A341/A341M Test Method for Direct Current Magnetic Properties of Soft Magnetic Materials Using D-C Permeameters and the
Point by Point (Ballistic) Test Methods
A582/A582M Specification for Free-Machining Stainless Steel Bars
A596/A596M Test Method for Direct-Current Magnetic Properties of Materials Using the Ballistic Method and Ring Specimens
A773/A773M Test Method for Direct Current Magnetic Properties of Low Coercivity Magnetic Materials Using Hysteresig-
raphs
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, 2013Oct. 1, 2018. Published July 2013October 2018. Originally approved in 1985. Last previous edition approved in 20072013 as
A838 – 02 (2007).(2013). DOI: 10.1520/A0838-02R13.10.1520/A0838-18.
2
Other product forms can be supplied to the chemistries listed in this specification; however, all other requirements shall be subject to negotiation between the producer
and the user.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. 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 ----------------------
A838 − 18
TABLE 1 Alloy Types
Nominal Composition, Weight Percent
Alloy Type
Carbon Chromium Silicon Sulfur Iron
1 0.05 17.5 0.50 0.30 balance
...
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