ASTM B958/B958M-23

Standard Specification for Extra-High-Strength and Ultra-High-Strength Class A Zinc–5% Aluminum-Mischmetal Alloy-Coated Steel Core Wire for Use in Overhead Electrical Conductors

SCOPE
1.1 This specification covers round, extra-high-strength, and ultra-high-strength, Class A coated zinc–5 % aluminum-mischmetal (Zn–5Al–MM) alloy-coated, steel core wire for use in Overhead Electrical Conductors.  
1.2 This specification covers wire of diameter from 0.0500 in. to 0.1900 in. inclusive or 1.27 mm to 4.82 mm inclusive.  
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the 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

• Status: Published
• Publication Date: 30-Sep-2023
• ICS: 77.140.65 - Steel wire, wire ropes and link chains
• Technical Committee: B01 - Electrical Conductors
• Drafting Committee: B01.05 - Conductors of Ferrous Metals

Relations

• Replaces: ASTM B958/B958M-22 - Standard Specification for Extra-High-Strength and Ultra-High-Strength Class A Zinc–5% Aluminum-Mischmetal Alloy-Coated Steel Core Wire for Use in Overhead Electrical Conductors
• Effective Date: 01-Oct-2023
• Refers: ASTM A370-24 - Standard Test Methods and Definitions for Mechanical Testing of Steel Products
• Effective Date: 01-Mar-2024
• Refers: ASTM A370-23 - Standard Test Methods and Definitions for Mechanical Testing of Steel Products
• Effective Date: 15-Sep-2023
• Referred By: ASTM B857-22 - Standard Specification for Shaped Wire Compact Concentric-Lay-Stranded Aluminum Conductors, Coated-Steel Supported (ACSS/TW)
• Effective Date: 01-Oct-2023
• Referred By: ASTM B232/B232M-22 - Standard Specification for Concentric-Lay-Stranded Aluminum Conductors, Coated-Steel Reinforced (ACSR)
• Effective Date: 01-Oct-2023
• Referred By: ASTM B856-22 - Standard Specification for Concentric-Lay-Stranded Aluminum Conductors, Coated Steel Supported (ACSS)
• Effective Date: 01-Oct-2023
• Referred By: ASTM B500/B500M-22 - Standard Specification for Metallic Coated or Aluminum Clad Stranded Steel Core for Use in Overhead Electrical Conductors
• Effective Date: 01-Oct-2023
• Referred By: ASTM B1006-17(2023) - Standard Specification for Electrical Overhead Conductor Code Word Names
• Effective Date: 01-Oct-2023
• Referred By: ASTM B711-22 - Standard Specification for Concentric-Lay-Stranded Aluminum-Alloy Conductors, Steel Reinforced (AACSR) (6201)
• Effective Date: 01-Oct-2023

Overview

ASTM B958/B958M-23: Standard Specification for Extra-High-Strength and Ultra-High-Strength Class A Zinc–5% Aluminum-Mischmetal Alloy-Coated Steel Core Wire for Use in Overhead Electrical Conductors defines the requirements for round, extra-high-strength, and ultra-high-strength steel core wire coated with zinc–5% aluminum-mischmetal (Zn–5Al–MM) alloy. This specification applies to wire diameters ranging from 0.0500 in. to 0.1900 in. (1.27 mm to 4.82 mm) and is intended for use in overhead electrical conductors, such as those found in power transmission and distribution networks.

The standard ensures that coated steel wire used as the core in overhead conductors meets stringent criteria for mechanical strength, coating quality, and uniformity, as well as dimensional and manufacturing consistency.

Key Topics

• Scope and Applicability

  • Covers round steel wire with Zn–5Al–MM alloy coating for enhanced corrosion resistance and mechanical performance
  • Includes both extra-high-strength (MA4) and ultra-high-strength (MA5) grades

• Material and Manufacturing

  • Steel made by open-hearth, electric furnace, or basic oxygen process
  • Wire is cold drawn and coated with Zn–5Al–MM alloy

• Chemical and Mechanical Properties

  • Composition requirements for steel and alloy coatings
  • Mechanical testing for tensile strength, elongation, and adherence of coating
  • Coating weight/mass specifications and evaluation via standardized test methods

• Dimensional Tolerances and Workmanship

  • Specification of precise wire diameters with defined permissible variations
  • Requirements for smooth, uniform, and defect-free coating

• Testing and Inspection

  • Includes mechanical, wrap, coating, and adherence tests
  • Procedures for inspection, rejection, and retesting of wire lots

• Ordering and Product Marking

  • Guidelines on specifying quantity, diameter, certification, package size, and product code
  • Requirements for tagging and labeling each package for traceability

Applications

Steel core wires that conform to ASTM B958/B958M-23 are primarily used in the construction of overhead electrical conductors, including ACSR and ACSS cables. These conductors are critical for:

• Electrical Power Transmission: Ensuring the durability and reliability of high-voltage overhead lines in utility grids.
• Distribution Networks: Supporting regional or urban electrical distribution with enhanced mechanical performance in challenging environments.
• Infrastructure Projects: Providing strength, stability, and corrosion resistance in exposed, harsh, or coastal environments.
• Retrofitting and Upgrading Lines: Suitable for projects designed to increase capacity or lifespan of existing transmission lines without extensive re-engineering.

The Zn–5Al–MM alloy coating provides improved resistance to atmospheric and abrasive corrosion, significantly extending the service life of the wire, especially in aggressive environments.

Related Standards

To ensure full compliance with ASTM B958/B958M-23 and maintain best practices in quality and performance, users should also consult the following standards:

• ASTM A90/A90M: Test Method for Weight [Mass] of Coating on Iron and Steel Articles with Zinc or Zinc-Alloy Coatings
• ASTM A370: Test Methods and Definitions for Mechanical Testing of Steel Products
• ASTM A751: Test Methods and Practices for Chemical Analysis of Steel Products
• ASTM B193: Test Method for Resistivity of Electrical Conductor Materials
• ASTM B750: Specification for GALFAN (Zinc–5% Aluminum-Mischmetal) Alloy in Ingot Form for Hot-Dip Coatings
• ASTM E1277: Test Method for Analysis of Zinc–5% Aluminum-Mischmetal Alloys by Inductively Coupled Plasma Atomic Emission Spectrometry

Conclusion

Compliance with ASTM B958/B958M-23 ensures that steel core wires for overhead electrical conductors maintain high mechanical strength, reliable performance, and long service life, supporting the critical infrastructure of electric power systems. Proper application and adherence to this standard facilitate reliable, efficient, and safe overhead transmission and distribution of electric power.

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: B958/B958M − 23
Standard Specification for
Extra-High-Strength and Ultra-High-Strength Class A
Zinc–5% Aluminum-Mischmetal Alloy-Coated Steel Core
Wire for Use in Overhead Electrical Conductors
This standard is issued under the fixed designation B958/B958M; 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 A370 Test Methods and Definitions for Mechanical Testing
of Steel Products
1.1 This specification covers round, extra-high-strength, and
A751 Test Methods and Practices for Chemical Analysis of
ultra-high-strength, Class A coated zinc–5 % aluminum-
Steel Products
mischmetal (Zn–5Al–MM) alloy-coated, steel core wire for
B193 Test Method for Resistivity of Electrical Conductor
use in Overhead Electrical Conductors.
Materials
1.2 This specification covers wire of diameter from
B750 Specification for GALFAN (Zinc-5 % Aluminum-
0.0500 in. to 0.1900 in. inclusive or 1.27 mm to 4.82 mm
Mischmetal) Alloy in Ingot Form for Hot-Dip Coatings
inclusive.
E1277 Test Method for Analysis of Zinc-5 % Aluminum-
Mischmetal Alloys by Inductively Coupled Plasma
1.3 The values stated in either SI units or inch-pound units
are to be regarded separately as standard. The values stated in Atomic Emission Spectrometry
E29 Practice for Using Significant Digits in Test Data to
each system may not be exact equivalents; therefore, each
system shall be used independently of the other. Combining Determine Conformance with Specifications
E47 Test Methods for Chemical Analysis of Zinc Die-
values from the two systems may result in non-conformance
with the standard. Casting Alloys (Withdrawn 1997)
2.2 Other Standard:
1.4 This standard does not purport to address all of the
GF-1 Standard Practice for Determination of Cerium and
safety concerns, if any, associated with its use. It is the
Lanthanum Compositions in Galfan Alloy (5 % Al-0.04 %
responsibility of the user of this standard to establish appro-
La-0.04 % Ce-Bal SHG Zn)
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
3. Terminology
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard- 3.1 Abbreviations:
ization established in the Decision on Principles for the 3.1.1 MM—mischmetal
Development of International Standards, Guides and Recom- 3.1.2 Zn–5Al–MM—zinc–5 % aluminum mischmetal alloy
mendations issued by the World Trade Organization Technical
3.2 Definitions of Terms Specific to This Standard:
Barriers to Trade (TBT) Committee.
3.2.1 lot, n—unless otherwise specified in the contract or
order, a lot shall consist of all coils of wire of the same
2. Referenced Documents
diameter and unit lengths submitted for inspection at the same
2.1 ASTM Standards:
time.
A90/A90M Test Method for Weight [Mass] of Coating on
3.2.2 product code, n—defines product coating type, coating
Iron and Steel Articles with Zinc or Zinc-Alloy Coatings
class, and strength grade.
3.2.2.1 Extra High Strength Grade Zn–5Al–MM, Class A
Coated—use Code MA4.
This specification is under the jurisdiction of ASTM Committee B01 on
Electrical Conductors and is the direct responsibility of Subcommittee B01.05 on
3.2.2.2 Ultra High Strength Grade Zn–5Al–MM, Class A
Conductors of Ferrous Metals.
Coated—use Code MA5.
Current edition approved Oct. 1, 2023. Published October 2023. Originally
approved in 2008. Last previous edition approved in 2022 as B958/B958M – 22.
DOI: 10.1520/B0958_B0958M-23.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or The last approved version of this historical standard is referenced on
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM www.astm.org.
Standards volume information, refer to the standard’s Document Summary page on Available from the International Lead Zinc Research Organization (ILZRO),
the ASTM website. 1822 NC Highway 54 East, Suite 120, Durham NC 27713, http://www.ilzro.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B958/B958M − 23
TABLE 2 Grade 4 Extra-High-Strength Tensile Requirements
4. Ordering Information
Stress Ultimate Elongation
4.1 Orders for material under this specification shall include
Specified Diameter, at 1 % Tensile in 10 in.,
the following information:
in. Extension, Strength, min %
min, kpsi min, kpsi
4.1.1 Quantity of each size,
0.0500 to 0.0899, incl 225 265 3.0
4.1.2 Wire diameter in inches or millimeter (Section 13),
0.0900 to 0.1199, incl 220 260 3.0
4.1.3 Certification, if required (Section 18),
0.1200 to 0.1399, incl 215 255 3.5
4.1.4 Test report, if required (Section 18),
0.1400 to 0.1900, incl 210 250 3.5
4.1.5 Package size (Section 19), and
4.1.6 Product code.
TABLE 3 Grade 4 Extra-High-Strength Tensile Requirements
[Metric]
5. Materials and Manufacture
Stress Ultimate Elongation
5.1 The base metal shall be steel produced by the open-
Specified Diameter, at 1 % Tensile in 250 mm,
hearth, electric furnace, or basic oxygen process. mm Extension, Strength, min %
min, MPa min, MPa
5.2 The wire shall be cold drawn and coated with
1.27 to 2.28, incl 1550 1825 3.0
Zn–5Al–MM alloy to produce the desired properties.
2.29 to 3.04, incl 1515 1790 3.0
3.05 to 3.55, incl 1480 1760 3.5
3.56 to 4.82, incl 1450 1725 3.5
6. Chemical Composition
6.1 The steel shall conform to the requirements prescribed
in Table 1.
TABLE 4 Grade 5 Ultra-High-Strength Tensile Requirements
Stress Ultimate Elongation
6.2 Chemical analysis of the steel shall be conducted in
Specified Diameter, at 1 % Tensile in 10 in.,
accordance with Test Methods and Practices A751.
in. Extension, Strength, min %
min, kpsi min, kpsi
6.3 The ingot form of zinc-5 % aluminum-mischmetal alloy
0.0500 to 0.0899, incl 230 285 3.0
shall conform to Specification B750.
0.0900 to 0.1199, incl 225 275 3.0
6.3.1 For a two-step coating operation where the first
0.1200 to 0.1399, incl 220 270 3.5
coating is zinc (hot-dip galvanized or electro-galvanized), the 0.1400 to 0.1900, incl 215 265 3.5
final bath may have an aluminum content of up to 7.2 %, to
prevent depletion of the aluminum content of the bath.
TABLE 5 Grade 5 Ultra-High-Strength Tensile Requirements
6.3.2 Method of Analysis—The determination of chemical
[Metric]
composition shall be made in accordance with suitable chemi-
Stress Ultimate Elongation
cal (Test Methods E47 for Tin), ICP Argon Plasma Spectro-
Specified Diameter, at 1 % Tensile in 250 mm,
metric (Practice E1277), or other methods. In case of dispute,
mm Extension, Strength, min %
the results secured by Practice E1277 shall be the basis of min, MPa min, MPa
acceptance. 1.27 to 2.28, incl 1580 1965 3.0
2.29 to 3.04, incl 1550 1900 3.0
6.3.3 A Method of Coating Material Analysis—Refer to
3.05 to 3.55, incl 1515 1860 3.5
Specification B750. In case of dispute, the results secured by
3.56 to 4.82, incl 1480 1825 3.5
Practice E1277 shall be the basis of acceptance.
7. Tensile Test
7.2 Tensile tests shall be conducted in accordance with Test
7.1 The Zn–5Al–MM alloy-coated steel core wire shall
Methods and Definitions A370, using the initial settings for
conform to the ordered tensile and elongation requirements
determining stress at 1 % extension given in Table 6 or Table
prescribed in Table 2, Table 3, Table 4, or Table 5 and a
7 of this specification.
minimum breaking strength (lb [N]) calculated from the
7.3 Test Specimens—The test specimens shall be free of
minimum required tensile and nominal wire diameter. The wire
bends or kinks other than the curvature resulting from the usual
tensile strength used to determine compliance to Table 2, Table
coiling operations. Any hand straightening necessary to permit
3, Table 4, or Table 5 shall be calculated using the actual wire
insertion of the specimen in the jaws of the testing machine
breaking strength and the nominal finished diameter of the
shall be performed by drawing between wood blocks or by
wire.
some other equally satisfactory means.
TABLE 1 Chemical Requirements TABLE 6 Initial Settings for Determining Stress at 1 % Extension
Element Composition, % Initial Stress, Initial Setting
Specified Diameter,
kpsi of Extensometer,
Carbon 0.50 to 1.00
in.
in./in.
Manganese 0.30 to 1.30
Phosphorus, max 0.035 0.0500 to 0.0899, incl 18 0.0005 (0.05 % extension)
Sulfur, max 0.045 0.0900 to 0.1199, incl 36 0.0010 (0.10 % extension)
Silicon 0.15 to 1.20 0.1200 to 0.1900, incl 54 0.0015 (0.15 % extension)
B958/B958M − 23
TABLE 7 Initial Settings for Determining Stress at 1 % Extension TABLE 9 Zn–5Al–MM Alloy Coating [Metric]
[Metric]
Area Density
Specified Diameter of Zn–5Al–MM Alloy Coating
Initial Stress, Initial Setting
Specified Diameter,
of Coated Wire, mm min of Uncoated Wire Surface,
MPa of Extensometer,
mm
g/m
mm/mm
1.27 to 1.52, incl 183
1.27 to 2.28, incl 125 0.0005 (0.05 % extension)
1.53 to 1.90, incl 198
2.29 to 3.04, incl 250 0.0010 (0.10 % extension)
1.91 to 2.28, incl 214
3.05 to 4.82, incl 375 0.0015 (0.15 % extension)
2.29 to 2.64, incl 229
2.65 to 3.04, incl 244
3.05 to 3.55, incl 259
3.56 to 4.57, incl 274
7.4 The nominal diameter requested shall be used to deter-
4.58 to 4.82, incl 305
mine the applicable strength specification from the tables.
8. Wrap Test
TABLE 10 Mandrel Size for Adherence Test
8.1 The material, as represented by the test specimens, shall
NOTE 1—Loosening or detachment during the adhesion test of
not fracture when the Zn–5Al–MM alloy-coated wire is
superficial, small particles of Zn–5Al–MM alloy formed by mechanical
wrapped at a rate not exceeding 15 turns/min in a helix of at
polishing of the surface of the coated wire shall not be considered cause
least eight turns around a cylindrical mandrel with a diameter
for rejection.
equal to four times the specified diameter of the wire under
Specified Wire Diameter, Ratio of Mand
...

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: B958/B958M − 22 B958/B958M − 23
Standard Specification for
Extra-High-Strength and Ultra-High-Strength Class A
Zinc–5% Aluminum-Mischmetal Alloy-Coated Steel Core
Wire for Use in Overhead Electrical Conductors
This standard is issued under the fixed designation B958/B958M; 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 round, extra-high-strength, and ultra-high-strength, Class A coated zinc–5 % aluminum-mischmetal
(Zn–5Al–MM) alloy-coated, steel core wire for use in Overhead Electrical Conductors.
1.2 This specification covers wire of diameter from 0.05000.0500 in. to 0.1900 in. inclusive or 1.271.27 mm to 4.82 mm inclusive.
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the 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.
2. Referenced Documents
2.1 ASTM Standards:
A90/A90M Test Method for Weight [Mass] of Coating on Iron and Steel Articles with Zinc or Zinc-Alloy Coatings
A370 Test Methods and Definitions for Mechanical Testing of Steel Products
A751 Test Methods and Practices for Chemical Analysis of Steel Products
B193 Test Method for Resistivity of Electrical Conductor Materials
B750 Specification for GALFAN (Zinc-5 % Aluminum-Mischmetal) Alloy in Ingot Form for Hot-Dip Coatings
E1277 Test Method for Analysis of Zinc-5 % Aluminum-Mischmetal Alloys by Inductively Coupled Plasma Atomic Emission
Spectrometry
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E47 Test Methods for Chemical Analysis of Zinc Die-Casting Alloys (Withdrawn 1997)
This specification is under the jurisdiction of ASTM Committee B01 on Electrical Conductors and is the direct responsibility of Subcommittee B01.05 on Conductors
of Ferrous Metals.
Current edition approved Oct. 1, 2022Oct. 1, 2023. Published November 2022October 2023. Originally approved in 2008. Last previous edition approved in 20192022
as B958/B958M – 19.B958/B958M – 22. DOI: 10.1520/B0958_B0958M-22.10.1520/B0958_B0958M-23.
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.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B958/B958M − 23
2.2 Other Standard:
GF-1 Standard Practice for Determination of Cerium and Lanthanum Compositions in Galfan Alloy (5 % Al-0.04 % La-0.04 %
Ce-Bal SHG Zn)
3. Terminology
3.1 Abbreviations:
3.1.1 MM—mischmetal
3.1.2 Zn–5Al–MM—zinc–5 % aluminum mischmetal alloy
3.2 Definitions of Terms Specific to This Standard:
3.2.1 lot, n—unless otherwise specified in the contract or order, a lot shall consist of all coils of wire of the same diameter and
unit lengths submitted for inspection at the same time.
3.2.2 product code, n—defines product coating type, coating class, and strength grade.
3.2.2.1 Extra High Strength Grade Zn–5Al–MM, Class A Coated—use Code MA4.
3.2.2.2 Ultra High Strength Grade Zn–5Al–MM, Class A Coated—use Code MA5.
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 diameter in inches or millimeter (Section 13),
4.1.3 Certification, if required (Section 18),
4.1.4 Test report, if required (Section 18),
4.1.5 Package size (Section 19), and
4.1.6 Product code.
5. Materials and Manufacture
5.1 The base metal shall be steel produced by the open-hearth, electric furnace, or basic oxygen process.
5.2 The wire shall be cold drawn and coated with Zn–5Al–MM alloy to produce the desired properties.
6. Chemical Composition
6.1 The steel shall conform to the requirements prescribed in Table 1.
TABLE 1 Chemical Requirements
Element Composition, %
Carbon 0.50 to 1.00
Manganese 0.30 to 1.30
Phosphorus, max 0.035
Sulfur, max 0.045
Silicon 0.15 to 1.20
Available from the International Lead Zinc Research Organization (ILZRO), 1822 NC Highway 54 East, Suite 120, Durham NC 27713, http://www.ilzro.org.
B958/B958M − 23
6.2 Chemical analysis of the steel shall be conducted in accordance with Test Methods and Practices A751.
6.3 The ingot form of zinc-5 % aluminum-mischmetal alloy shall conform to Specification B750.
6.3.1 For a two-step coating operation where the first coating is zinc (hot-dip galvanized or electro-galvanized), the final bath may
have an aluminum content of up to 7.2 %, to prevent depletion of the aluminum content of the bath.
6.3.2 Method of Analysis—The determination of chemical composition shall be made in accordance with suitable chemical (Test
Methods E47 for Tin), ICP Argon Plasma Spectrometric (Practice E1277), or other methods. In case of dispute, the results secured
by Practice E1277 shall be the basis of acceptance.
6.3.3 A Method of Coating Material Analysis—Refer to Specification B750. In case of dispute, the results secured by Practice
E1277 shall be the basis of acceptance.
7. Tensile Test
7.1 The Zn–5Al–MM alloy-coated steel core wire shall conform to the ordered tensile and elongation requirements prescribed in
Table 2, Table 3, Table 4, or Table 5 and a minimum breaking strength (lb [N]) calculated from the minimum required tensile and
nominal wire diameter. The wire tensile strength used to determine compliance to Table 2, Table 3, Table 4, or Table 5 shall be
calculated using the actual wire breaking strength and the nominal finished diameter of the wire.
7.2 Tensile tests shall be conducted in accordance with Test Methods and Definitions A370, using the initial settings for
determining stress at 1 % extension given in Table 6 or Table 7 of this specification.
7.3 Test Specimens—The test specimens shall be free of bends or kinks other than the curvature resulting from the usual coiling
operations. Any hand straightening necessary to permit insertion of the specimen in the jaws of the testing machine shall be
performed by drawing between wood blocks or by some other equally satisfactory means.
7.4 The nominal diameter requested shall be used to determine the applicable strength specification from the tables.
8. Wrap Test
8.1 The material, as represented by the test specimens, shall not fracture when the Zn–5Al–MM alloy-coated wire is wrapped at
a rate not exceeding 15 turns/min in a helix of at least eight turns around a cylindrical mandrel with a diameter equal to four times
the specified diameter of the wire under test, 65 %. The edge-to-edge spacing of consecutive turns shall not exceed two times the
diameter of the wire.
9. Coating Test
Table 8 or Table 9.
9.1 The Zn–5Al–MM alloy-coated wire shall conform to the coating requirements prescribed in
9.2 The coating test shall be conducted in accordance with Test Method A90/A90M.
10. Adherence of Coating Test
10.1 The Zn–5Al–MM alloy-coated wire shall be capable of being wrapped in a close helix at a rate not exceeding 15 turns ⁄min
TABLE 2 Grade 4 Extra-High-Strength Tensile Requirements
Stress Ultimate Elongation
Specified Diameter, at 1 % Tensile in 10 in.,
in. Extension, Strength, min %
min, kpsi min, kpsi
0.0500 to 0.0899, incl 225 265 3.0
0.0900 to 0.1199, incl 220 260 3.0
0.1200 to 0.1399, incl 215 255 3.5
0.1400 to 0.1900, incl 210 250 3.5
B958/B958M − 23
TABLE 3 Grade 4 Extra-High-Strength Tensile Requirements
[Metric]
Stress Ultimate Elongation
Specified Diameter, at 1 % Tensile in 250 mm,
mm Extension, Strength, min %
min, MPa min, MPa
1.27 to 2.28, incl 1550 1825 3.0
2.29 to 3.04, incl 1515 1790 3.0
3.05 to 3.55, incl 1480 1760 3.5
3.56 to 4.82, incl 1450 1725 3.5
TABLE 4 Grade 5 Ultra-High-Strength Tensile Requirements
Stress Ultimate Elongation
Specified Diameter, at 1 % Tensile in 10 in.,
in. Extension, Strength, min %
min, kpsi min, kpsi
0.0500 to 0.0899, incl 230 285 3.0
0.0900 to 0.1199, incl 225 275 3.0
0.1200 to 0.1399, incl 220 270 3.5
0.1400 to 0.1900, incl 215 265 3.5
TABLE 5 Grade 5 Ultra-High-Strength Tensile Requirements
[Metric]
Stress Ultimate Elongation
Specified Diameter, at 1 % Tensile in 250 mm,
mm Extension, Strength, min %
min, MPa min, MPa
1.27 to 2.28, incl 1580 1965 3.0
2.29 to 3.04, incl 1550 1900 3.0
3.05 to 3.55, incl 1515 1860 3.5
3.56 to 4.82, incl 1480 1825 3.5
TABLE 6 Initial Settings for Determining Stress at 1 % Extension
Initial Stress, Initial Setting
Specified Diameter,
kpsi of Extensometer,
in.
in./in.
0.0500 to 0.0899, incl 18 0.0005 (0.05 % extension)
0.0900 to 0.1199, incl 36 0.0010 (0.10 % extension)
0.1200 to 0.1900, incl 54 0.0015 (0.15 % extension)
TABLE 7 Initial Settings for Determining Stress at 1 % Extension
[Metric]
Initial Stress, Initial Setting
Specified Diameter,
MPa of Extensometer,
mm
mm/mm
1.27 to 2.28, incl 125 0.0005 (0.05 % extension)
2.29 to 3.04, incl 250 0.0010 (0.10 % extension)
3.05 to 4.82, incl 375 0.0015 (0.15 % extension)
around a cylindrical mandrel having a diameter as prescribed in Table 10 or Table 11, without cracking or flaking the
...