This standard outlines the specifications for plain hard-drawn steel wire supplied in coil form for prestressed concrete applications, focusing on as-drawn wire condition. It details manufacturing methods, chemical and mechanical property criteria, testing protocols, marking, and packaging requirements, ensuring consistent quality for prestressed concrete elements.
Overview
This standard outlines the specifications for plain hard-drawn steel wire supplied in coil form for prestressed concrete applications, focusing on as-drawn wire condition. It details manufacturing methods, chemical and mechanical property criteria, testing protocols, marking, and packaging requirements, ensuring consistent quality for prestressed concrete elements.
Audience
Contents
Structure
This section defines the terminology related to plain hard drawn steel wire for prestressed concrete and specifies that the standard applies to cold-drawn wire supplied as coils. It includes dimensional tolerances on nominal diameter, chemical composition limits (such as maximum sulphur and phosphorus content), and quality control formulas to ensure compliance.
Clarifies the standard definitions of terms including wire diameter, tensile strength, proof stress, chemical composition, and tolerances, ensuring uniform understanding throughout the document.
Describes the acceptable steelmaking processes (including open hearth, electric duplex, acid Bessemer, basic oxygen methods), requirements for mill test certificates, mechanical and chemical property controls, and traceability obligations for coils and bundles.
Specifies chemical composition limits, tensile strength requirements by nominal wire diameter, ductility testing protocols, and acceptance criteria based on statistical evaluation of test results.
Details the permitted deviations in wire diameter measurements, procedures for ovality assessment, and nominal mass tolerances for wires exceeding ovality thresholds, ensuring dimensional precision.
Defines the minimum tensile strength values for various wire diameters, lot acceptance conditions based on sampling and statistical analysis of test outcomes, and the formulae used to verify compliance.
Outlines the number of specimens to be tested per coil, ductility and reverse bend test requirements, tensile test methods, and criteria for permissible defects in specimens.
Specifies the number of coils to be sampled based on lot size, and the criteria for accepting or rejecting a lot based on compliance of all tested characteristics.
Describes standards governing delivery, inspection, and testing (referencing IS 1387-1967), requirements for mill records, permissible defective specimen limits in ductility tests, marking regulations, and notes on heat treatment and tensile strength adjustments.
Specifies the mandatory information to be included on tags attached to wire coils or bundles, including manufacturer identification, coil length or mass, nominal wire diameter, and batch or coil number, ensuring full traceability.
Frequently Asked
IS 1785 Part 2 mandates minimum tensile strength values for plain hard-drawn steel wire used in prestressed concrete as follows:
| Wire Diameter (mm) | Minimum Tensile Strength (N/mm²) |
|---|---|
| 2.50 | 1800 |
| 3.00 | 1765 |
| 4.00 | 1715 |
| 5.00 | 1570 |
Additionally, the proof stress should be at least 75% of the minimum tensile strength. The wires are supplied in the as-drawn condition without stress relief, and tensile strength values correspond to nominal diameter measured according to the standard.
The standard permits steel production via the following methods for manufacturing wire suitable for prestressed concrete:
Use of other steelmaking processes requires prior purchaser approval. The steel must be cold-drawn from these steels, and welds are not allowed in the final wire.
Proof stress testing is conducted per IS 1521-1972 by applying load until the extensometer records a 1.0% elongation of the gauge length; the stress at this point must be at least 75% of the minimum tensile strength. Additionally, a reverse bend ductility test requires the wire to endure three bends (bending in one direction followed by the opposite) without cracking or breaking, ensuring sufficient flexibility.
As per IS 1785 Part 2 with the latest amendment, the maximum permissible content is 0.040% by weight for both sulphur and phosphorus. These limits help maintain steel quality suitable for prestressed concrete wire applications. Statistical quality control further ensures that chemical composition test results conform within specified ranges.
Each wire coil or bundle must be securely tagged with details including the manufacturer's identification, coil length or mass, nominal wire diameter, and batch or coil number. This labeling system enables tracing every finished wire back to the original cast or billet, supporting quality assurance and inventory control. The use of the Standard Mark and access to production records are also regulated to maintain traceability.
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