ASTM B976-21

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Designation: B976 − 11 (Reapproved 2015) B976 − 21
Standard Specification for
Fiber Reinforced Aluminum Matrix Composite (AMC) Core
Wire for Aluminum Conductors, Composite Reinforced
(ACCR)Conductors Aluminum Matrix Composite Reinforced
(ACAMCR) (formerly known as ACCR)
This standard is issued under the fixed designation B976; 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 fiber reinforced, aluminum matrix composite core wire used for mechanical reinforcement in the
manufacture of aluminum conductor, aluminum matrix composite reinforced (ACCR).(ACAMCR). This wire consists of
continuous filament fibers of aluminum oxide in a matrix of aluminum.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.2.1 Exception—Some non-standard SI units provided for information only do not appear in brackets.
1.3 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.
1.4 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 The following documents of the issue in effect on date of material purchase form a part of this specification to the extent
referenced herein.
2.2 ASTM Standards:
B193 Test Method for Resistivity of Electrical Conductor Materials
B830 Specification for Uniform Test Methods and Frequency
D3552 Test Method for Tensile Properties of Fiber Reinforced Metal Matrix Composites
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
This specification is under the jurisdiction of ASTM Committee B01 on Electrical Conductors and is the direct responsibility of Subcommittee B01.07 on Conductors
of Light Metals.
Current edition approved Oct. 1, 2015Oct. 1, 2021. Published October 2015October 2021. Originally approved in 2011. Last previous edition approved in 20112015 as
B976B976 – 11 (2015). – 11. DOI: 10.1520/B0976-11R15.10.1520/B0976-21.
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
B976 − 21
3.1.1 ACAMCR, n—Aluminum Conductor Aluminum Matrix Composite Reinforced, a concentric-lay-stranded conductor made up
of outer aluminum strands of hard, heat resistant aluminum wires and a core of round, aluminum matrix composite wire(s), for
use as overhead electrical conductors.
3.1.2 AMC, n—Aluminum Matrix Composite, a material consisting of two constituents: the first a series of continuous fibers of
aluminum oxide which is embedded in the second constituent of aluminum metal.
3.1.3 fiber reinforced aluminum matrix composite wire, n—a wire consisting of two constituents: the first a number of continuous
fibers of aluminum oxide along the axis of the wire, which is embedded in the second constituent of aluminum metal, as shown
in Fig. 1.
3.1.4 lot, n—unless otherwise specified in the contract or order, a lot shall consist of all coils of wire of the same diameter
submitted for inspection at the same time.
3.1.5 production unit, n—a reel, spool, or other package of wire that represents a single usable length.
3.1.6 sample, n—the production unit(s) from which a test specimen(s) has been removed, and which is considered to have
properties representative of the lot.
3.1.7 specimen, n—a length of wire removed for test purposes.
3.1.8 tow, n—a bundle, containing multiple fibers.
3.1.7 AMC, n—Aluminum Matrix Composite, a material consisting of two constituents: the first a series of continuous fibers of
aluminum oxide which is embedded in the second constituent of aluminum metal.
3.1.8 ACCR, n—Aluminum Conductor Composite Reinforced, a concentric-lay-stranded conductor made up of outer aluminum
strands of hard, heat resistant aluminum wires and a core of round, aluminum matrix composite wire(s), for use as overhead
electrical conductors.
4. Ordering Information
4.1 Orders for material under this specification shall include the following information:
4.1.1 Quantity of each size,
4.1.2 Wire size (see 8.1),
4.1.3 Place of inspection (see 11.1),
4.1.4 Package size and type (see 12.1),
4.1.5 Special package marking.
NOTE 1—Dark Phases are fiber viewed end-on and the light phase is aluminum matrix. The equivalent diameter of the fibers is approximately 470 μin.
(12 μm).470 μin. (12 μm).
FIG. 1 Polished Cross-section of an Aluminum Matrix Composite Wire
B976 − 21
5. Materials and Manufacture
5.1 The fiber reinforcement shall be continuous tows of aluminum oxide.
5.2 The core wires shall be of such quality and purity that the finished product shall have the approximate properties and
characteristics prescribed in this specification, including breaking load, elongation, modulus properties, and electrical resistivity
requirements set forth in Table 1.
6. Tensile Test
6.1 Before stranding, the composite core wire of any diameter shall conform to the tensile breaking load requirements set forth
in Table 2 (see Explanatory Note 1).
6.2 Test Method—Tensile testing of metal matrix composite materials is covered by Test Method D3552, including the need for
stringent test frame alignment. However, this standard does not specify testing of round metal matrix composite wire samples.
Thus, for AMC core wire samples, the tensile test shall use a minimum gauge length of 24 in. (610 mm) (see Explanatory Note
2). Each end of the wire shall be adhesively bonded to a depth of 4 in. (100 mm) into a 6 in. (150 mm) long steel gripping tube.
A Hi-flex epoxy is suggested such as Scotch-Weld DP-810 Hi-flex epoxy adhesive. The test machine gripping jaws shall grip the
end section of the tube that contains no wire. Direct gripping of the core wire in the test machine jaws without end tubes is not
permitted, unless the tester can demonstrate the effect of direct gripping on the wire does not cause failure of the wire within the
gripping length. The cross-head speed shall provide a strain rate of
0.002in./in./min0.002 in. ⁄in. ⁄min (0.002 mm/mm/min).
6.3 Test Specimens—The test specimens shall be free of sharp bends, dents or kinks other than the curvature resulting from the
packaging operations.
7. Density and Resistivity
7.1 For the purposes of calculating mass per unit length, cross-sections, and so forth, the density of the composite wire at
3 3
20°C20 °C shall be taken as 0.122 lb/in. (3370 kg/m ).
7.2 Electrical resistivity, determined on samples selected and tested in accordance with Test Method B193, shall not exceed 43.2
Ω·cmil/ft (0.0718 Ω·mm /m) at 68°F (20°C).68 °F (20 °C).
7.3 Equivalent conductivity; the wire shall meet or exceed 24.0 % 24.0 % IACS at 68°F (20°C).68 °F (20 °C).
TABLE 1 Typical Physical Properties
NOTE 1—See Explanatory Note 1
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