ASTM A838/A838M-97

Standard Specification for Free-Machining Ferritic Stainless Soft Magnetic Alloys for Relay Applications

SCOPE
1.1 This specification covers free-machining ferritic stainless soft magnetic materials produced or supplied expressly for use in magnetic cores and other parts requiring a high permeability stainless steel having low-coercive force and low-residual magnetism.
1.1.1 The specific alloy types have corrosion resistance similar to AISI Type 430F and Type 430F Specification A582.
1.1.2 Two specific type alloys are covered in Table 1.
1.2 This specification covers these alloy types supplied in billet or bar form in shapes such as rounds, squares, hexagons, octagons, or special shapes.
1.3 Certain cold finish round bar products are capable of being supplied to required magnetic characteristics such as low-residual magnetism. Other product forms of these alloy types can not be produced having equivalent low-residual magnetism; hence, final machined parts shall be heat treated as recommended by the producer.
1.4 The following safety hazard caveat pertains only to the test method portions in Annex A1 of this specification. This standard does not purport to address all of 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.  
1.5 Magnetic properties are expressed in cgs-emu units followed by the SI unit equivalent enclosed in parentheses.

General Information

• Status: Historical
• Publication Date: 09-Apr-1997
• ICS: 77.140.40 - Steels with special magnetic properties
• Technical Committee: A06 - Magnetic Properties
• Drafting Committee: A06.02 - Material Specifications

Standards Content (Sample)

STD.ASTH A838/A838H-ENGL I,997 - 0759530 ObCl927’i
AMERICAN SOCIETY FOR TESTING AND MATERIALS
Designation: A 838/A 838M - 97
100 Barr Harbor Dr., West Ccmshohocken. PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Specification for
Free-Machining Ferritic Stainless Soft Magnetic Alloy Bar for
Relay Applications’
This standard is issued under the fixed designation A 838/A 838#, the number immediately following the d&nation 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 sina the last revision or reapproval.
A 341 Test Method for Direct Current Magnetic Proper-
1. Scope
ties of Materials Using D-C Permeameters and the
1.1 This specification covers free-machining ferritic stain-
Ballistic Test Method3
less soft magnetic alloy produced or supplied expressly in
A 582 Specification for Free-Machining Stainless Steel
cold-finished bar form for use in magnetic cores and other
parts requiring a high permeability, low-coercivity stainless
A 596 Test Method for Direct-Current Magnetic Proper-
steel.
ties of Materials Using the Ballistic Method and Ring
1.1.1 This specification does not cover either cast parts or
Specimens3
parts produced by powder metallurgy techniques.
A 773 Test Method for D-C Magnetic Properties of
1.2 Two specific alloy types are covered. The primary
Materials Using Ring and Permeameter Procedures with
constituents are shown in Table 1. These types have corro-
D-C Electronic Hysteresigraphs3
sion resistance similar to AISI Type 430F and Type 430F
E 1019 Test Methods for Determination of Carbon,
ASTM Specification A 582.
Sulfur, Nitrogen, and Oxygen in Steel and in Iron,
1.3 This specification covers only these alloy types sup-
Nickel, and Cobalt Alloys5
plied in cold-finished bars in cross-sectional shapes such as
2.2 Other Standard:
rounds, squares, hexagons, and octagons with diameters
IEC Publication 404-7 “Methods of Measurement of the
(diagonals) greater than or equal to 0.250 in. t6.35 mm] and
Coercivity of Magnetic Materials in an Open Magnetic
less than or equal to 1.625 in. [41.28 mm].’
Circuit*
1.4 Certain cold-finished round bar products are capable
of being supplied mill annealed to required magnetic prop
3. Terminology
et-ties 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]. 3.1 The terms and symbols used in this specification are
Other products of these alloys cannot be mill annealed to defined in Terminology A 340.
produce equivalently low coercivity; hence, the final ma-
chined parts should be heat treated as recommended by the
4. classilication
producer.
4.1 Two specific alloy types are covered:
1.5 The values stated in either customary (cgs-emu and
4.2 Grades, Alloy Type l-The standard grades of this
inch-pound) units or SI units are to be regarded separately as
alloy type are distinguished by the as-supplied condition,
standard. Within the text, the SI units are shown in brackets.
coercivity, and nominal mechanical hardness and are listed
The values stated in each system are not exact equivalents;
in Table 2.
therefore, each system shah be used independently of the
4.3 Grades, Alloy Type 2-The standard grades of this
other, Combining values from the two systems may result in
alloy type are distinguished by the as-supplied condition,
nonconformance with this specification.
coercivity, and nominal mechanical hardness and are listed
in Table 3.
2. Referenced Documents
5. Ordering Information
2.1 ASTM Standards:
5.1 Purchase orders for material under this specification
A 34 Practice for Sampling and Procurement Testing of
shah include the following information to adequately de-
Magnetic Materials3
scribe the desired product:
A 340 Terminology of Symbols and Definitions Relating
5.1.1 Reference to this specification and year of issue/
to Magnetic Testing3
revision.
5.1.2 Ahoy type and grade (Section 4),
I This specitication is under the jurixktion of ASTM Committee A-6 on 5.1.3 Form and condition,
Magnetic Properties and is the direct responsibility of Subcommittee A06.02 on
5.1.4 Dimensions and tolerances (Section 9),
Materials Specifications.
Current edition approved April IO, 1997. Published December 1997. Originally
published as A 838 - 85. Last previous edition A 838 - 9Oa
2Other product forms can be supplied to the chemistries listed in this 4 Annual Book of ASTM Stana.ard~, Vol 0 I .03.
5 Annual Book of ASTM Stamiards, VolO3.06.
specification, however, all other requirements shall bc subject to negotiation
between the producer and the purchaser. 6 Available from American National Standards Institute, 1 I W. 42nd St. 13th
Floor, New York, NY 10036.
3 Annual Book oJASTM Siandarth, VolO3.04.
1

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