Steel Sheet, Terne (Lead-Tin Alloy) Coated by the Hot-Dip Process

A308/A308M-10: Navigating the Standard for Terne (Lead-Tin Alloy) Coated Steel Sheet

For professionals in metal fabrication, automotive manufacturing, and construction, understanding material specifications is paramount to ensuring product integrity and performance. The ASTM A308/A308M-10 standard provides an authoritative framework for specifying steel sheet coated with a lead-tin alloy, commonly known as terne. This essential document ensures that terne-coated steel sheet meets critical requirements for solderability and corrosion resistance, making it a proven choice for demanding applications.

What is A308/A308M-10?

ASTM A308/A308M-10 is the industry-leading standard that defines the requirements for steel sheet coated with a lead-tin alloy (terne metal) through a hot-dip process. Its primary purpose is to ensure consistent quality and performance characteristics, specifically addressing properties like ease of soldering and a degree of corrosion resistance, particularly in environments where gasoline exposure is a concern. This comprehensive standard is vital for procuring and utilizing terne-coated steel sheet reliably.

Scope & Purpose

This standard governs the production and procurement of steel sheet, available in coils and cut lengths, that has undergone a hot-dip coating process with a lead-tin alloy. It specifies requirements for various steel types, including commercial steel, deep drawing steel, extra deep drawing steel, and structural steel, as well as different coating weights. While this standard details the terne coating process and its resulting properties, it references other ASTM standards for general requirements related to metallic-coated steel sheet.

Who Must Comply?

• • Primary audience: Materials Engineers, Metallurgists, Quality Control Inspectors, Production Managers, Purchasing Agents, and Design Engineers.
• • Industries affected: Steel Production, Metal Fabrication, Automotive Manufacturing (especially fuel tanks), Construction (roofing), Appliance Manufacturing, and any industry utilizing stamped parts requiring solderability and corrosion resistance.
• • Compliance nature: Voluntary, but highly recommended and often contractually mandated by purchasers for quality assurance.
• • Enforcement: Typically enforced through contractual agreements and quality audits by purchasers or third-party inspection agencies.

Key Requirements Overview

Professionals utilizing A308/A308M-10 must ensure adherence to several core provisions:

• • The standard requires specific classifications for the base metal, including Commercial Steel (CS), Deep Drawing Steel (DDS), Extra Deep Drawing Steel (EDDS), and Structural Steel (SS), with options for different grades.
• • Key provisions include detailed specifications for the weight of the lead-tin alloy coating, expressed by coating designation (e.g., LT25, LT75), which directly influences performance.
• • The standard addresses the option of pre-deposited electrolytic nickel plating to enhance coating uniformity and corrosion resistance.
• • It mandates that material furnished must conform to applicable requirements of the latest issue of Specification A924/A924M for general requirements of hot-dip metallic-coated steel sheet.
• • Requirements for base metal chemical composition and mechanical properties (for structural steel) are outlined, with typical properties for other grades provided for informational purposes.

Related Standards & References

To fully implement A308/A308