ASTM A421/A421M-21 pdf free download.Standard Specification for Stress-Relieved Steel Wire for Prestressed Concrete.
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 7\pe BA wire is used for applications in which cold-end deformation is used for anchoring purposes (Button Anchorage), and
1.1.2 lype 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 A421 M).
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.
5. Mechanical Property Requirements
5.1 Tensile Strength—The tensile strength of Type BA wire and Type WA wire shall conform to the requirements prescribed in Table 1, and shall be determined as prescribed in Test Methods and Definitions A370, including Annex A4.
5.2 weld Strength:
5.2.1 The minimum yield strength for all wire, measured by the 1.0 % extension under load method, shall noL be less than 85 % of the specified minimum tensile strength.
5.2.2 The extension under load shall be measured by an exiensometer calibrated with the smallest division not larger than 0.0001 in./in. 10.0001 mm/mm] of gauge length.
5.2.3 The initial load corresponding to the initial stress prescribed in Table 2 shall be applied to the test specimen, at which time the extensometer is attached and adjusted to a reading of 0.001 in./in. [0.001 rnrn/mrnj of gauge length. The load shall then be increased until the extensometer indicates an extension of 1 %. The load for this extension shall be recorded. The stress corresponding to this load shall meet the requirements for stress at I % extension prescribed in Table 2.
5.3 Elongation—The total elongation under load of all wire shall not be less than 4.0 % when measured in a gauge length of 10 in. [250 mml. The elongation shall be determined by an extensometer which is placed on the test specimen after a load corresponding to the initial stress prescribed in Table 2 is applied. If the fracture takes place outside of the gauge length and the elongation so measured meets the minimum requirements, no further testing shall be required. if the elongation is less than the minimum requirements, the test shall be considered an invalid test and a retest made.
ASTM A421/A421M pdf download.