Metallic Coated Carbon Steel Wire, Coated at Size and Drawn to Size for Mechanical Springs

A764: Standard Specification for Metallic Coated Carbon Steel Wire, Coated at Size and Drawn to Size for Mechanical Springs

For engineers and designers specifying materials for mechanical springs, ensuring consistent performance, durability, and corrosion resistance is paramount. ASTM A764 provides an authoritative framework for metallic-coated carbon steel wire, offering proven quality for critical spring applications where standard materials might fall short. This essential standard ensures that wire used in the production of mechanical springs meets stringent requirements for coating integrity and mechanical properties.

What is A764?

ASTM A764 is a comprehensive standard specification that outlines the requirements for round, metallic-coated, hard-drawn carbon steel spring wire. Developed by ASTM International, it details the properties and quality necessary for manufacturing mechanical springs and wire forms that are intended for applications not demanding extremely high stress or fatigue life. Its primary purpose is to establish a reliable benchmark for material selection and manufacturing processes, ensuring predictable performance in diverse industrial and consumer products.

Scope & Purpose

This standard governs the production and quality control of metallic-coated carbon steel wire intended for mechanical spring manufacturing. It specifies requirements for the base metal, metallic coating types (including aluminum, zinc, and zinc-aluminum alloy), coating finishes (applied before or after drawing), and mechanical properties such as tensile strength and wrap test performance. The scope explicitly excludes wire intended for high-stress or high-fatigue applications, focusing instead on general-purpose mechanical springs and wire forms where corrosion resistance and moderate strength are key.

Who Must Comply?

• • Primary audience: Materials Engineers, Metallurgists, Quality Control Inspectors, Production Engineers, and Chemical Engineers involved in the specification, manufacturing, or quality assurance of spring wire and components.
• • Industries affected: Manufacturing, Automotive, Aerospace, Industrial Equipment, Consumer Goods, and any sector utilizing mechanical springs.
• • Compliance nature: While often voluntary, compliance with A764 is frequently a contractual requirement or a de facto industry standard for quality-conscious manufacturers and their suppliers.
• • Enforcement: Compliance is typically self-enforced by manufacturers and verified through quality control testing. Purchasers may also mandate compliance and conduct their own audits or require third-party certifications.

Key Requirements Overview

• • The standard requires the base carbon steel wire to be of good commercial quality, processed to ensure freedom from defects.
• • Professionals must ensure the wire conforms to specified metallic coating types (e.g., aluminum, zinc, Zn-Al alloy) and classes, with defined minimum coating weights.
• • Key provisions include stringent mechanical property requirements, such as tensile strength ranges and wrap test performance to verify coating adhesion and ductility.
• • The standard mandates specific testing methodologies for coating weight and mechanical properties to ensure consistent, verifiable results.
• • Dimensional tolerances for wire diameter are clearly defined to ensure interchangeability and proper fit in spring designs.

Related Standards & References

ASTM A764 frequently integrates with other industry-leading standards for a comprehensive approach to material quality. Complementary standards include:

• • ASTM A370: Provides standardized methods for mechanical testing of steel products, including tensile and wrap tests, essential for verifying compliance with A764's mechanical property requirements.
• • ASTM A90/A90M and A428/A428M: