Resources & Guides / Building Codes & Standards / ASTM & UL Standards / ASTM A493
ASTM A493
Steel, Stainless and Heat-Resisting, Wire and Wire Rods for Cold Heading and Cold Forging
Overview
ASTM A493 governs the properties of stainless steel and heat-resisting steel wire and wire rods used as raw material for the production of fasteners (bolts, screws, studs) and other cold-formed components. The wire is the precursor material that manufacturers purchase and then cold head or cold forge into finished products. This standard covers various stainless steel grades including austenitic (300 series like 304, 316), ferritic (400 series), and precipitation hardening grades.
Primary Building Applications
- Raw material for stainless steel fasteners (bolts, screws, studs)
- Architectural cable assemblies and tension rods
- Curtain wall and facade fastening systems
- Corrosion-resistant anchors for exterior applications
- Marine and coastal construction hardware
Critical for Preventing Galvanic Corrosion
A critical application is in aluminum-framed curtain walls or architectural metal panel systems. Using fasteners made from A493-compliant 300-series stainless steel is essential to prevent galvanic corrosion. Using carbon steel fasteners in aluminum assemblies causes the aluminum to corrode preferentially, compromising structural integrity and aesthetics. Type 304 or 316 stainless steels are much closer to aluminum on the galvanic series, making them compatible and preventing rust staining on architectural surfaces.
Specification Guidance
It's crucial to understand that ASTM A493 covers the raw wire material, not the finished fastener. A complete specification should call out both the finished product standard (e.g., "fasteners to comply with ASTM F593") and add a clause requiring that "material used for fabrication shall conform to ASTM A493, Grade 316." This two-tiered approach ensures both the final product geometry and the underlying material chemistry are controlled, which is especially critical for fasteners in highly corrosive or structurally significant exposed locations.