This specification covers two types of uncoated stress-relieved round high-carbon steel wire commonly used in prestressed linear concrete construction. These two types are the type BA used for applications in which cold-end deformation is used for anchoring purposes and type WA wire which is used for application in which the ends are anchored by wedges, no cold-end deformation of the wire is involved. Required tensile strength, yield strength, and elongation shall be evaluated using stress-relaxation test. Heat analysis shall be used to determine the percentage of specified elements especially sulfur and phosphorus to meet the required chemical composition.

1.1 This specification covers two types of stress-relieved round high-carbon steel wire used in prestressed concrete construction, as follows:

1.1.1 Type BA wire is used for applications in which cold-end deformation is used for anchoring purposes (Button Anchorage), and

1.1.2 Type WA wire is used for application in which the ends are anchored by wedges, and no cold-end deformation of the wire is involved (Wedge Anchorage).

1.2 A supplementary requirement (S1) is provided for use where low-relaxation wire and relaxation testing for that product is required by the purchaser. The supplementary requirement applies only when specified in the purchase order or contract.

1.3 This specification is applicable for orders in either inch-pounds units (as Specification A421) or in SI units (as Specification A421M).

1.4 The values stated in either inch-pound or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. 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 specification.

1.5 The text of this specification references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables) shall not be considered as requirements of the specification.

1.6 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.