ASTM A490 Structural Bolts

ASTM A490 High Strength Structural Bolts — Quenched & Tempered Heavy Hex | 1/2″–1-1/2″

ASTM A490 structural bolts are the highest strength heavy hex structural bolts used in steel construction, delivering a minimum tensile strength of 1040 MPa (150 ksi). Manufactured to ASTM A490 specification (now technically ASTM F3125 Grade A490), these quenched and tempered alloy steel bolts are engineered for critical structural connections requiring maximum load capacity. Available in Type 1 (alloy steel) and Type 3 (weathering steel) variants.

Material & Specifications

Size Range	1/2″ to 1-1/2″ (M12 to M36 equivalent)
Standard	ASTM A490 / ASTM F3125 Grade A490, AISC 360, RCSC Specification
Material	Type 1: Quenched & Tempered Alloy Steel; Type 3: Weathering Steel Alloy
Surface / Coating	Black/Plain (standard — NOT galvanized per ASTM A490), Dacromet (alternative coating)
Tensile Strength	≥ 1040 MPa (150 ksi)
Yield Strength	≥ 896 MPa (130 ksi)
Head Type	Heavy hex head (identical to ASTM A325 dimensions)

Surface Treatment & Zinc Coating Quality

At BoltNutsPlus, we understand that surface treatment is critical to fastener longevity and performance. Our products undergo rigorous coating processes to ensure maximum corrosion resistance and durability. We offer five premium coating options, each tested to international standards:

• Hot-Dip Galvanizing (HDG) — Thick zinc layer (50-120μm) providing superior long-term corrosion protection for outdoor, marine, and industrial environments. Compliant with ISO 1461 / ASTM A153 standards. Salt spray resistance: 500-1,000+ hours. Ideal for structural steel assemblies exposed to harsh weather.
• Electroplated Zinc Blue-White (Zn Blue/White) — Bright, clean silver-blue appearance with 5-15μm zinc layer. Cr3+ passivation technology, fully RoHS compliant. Ideal for indoor machinery, electronics, and general-purpose applications requiring aesthetic appeal and moderate corrosion resistance.
• Color Zinc / Yellow Zinc (Iridescent Passivation) — Multi-colored iridescent passivation film offering enhanced corrosion resistance (100-200 hours salt spray) with a distinctive golden finish. Widely preferred in automotive, agricultural equipment, and construction machinery sectors for its balanced protection and visual appeal.
• Dacromet Coating — Advanced water-based zinc-chromium coating technology with NO hydrogen embrittlement risk. Provides 1,000+ hours salt spray resistance, making it the preferred choice for high-strength fasteners in extreme environments. Environmentally friendly (no heavy metal discharge), RoHS/ELV compliant, ideal for automotive and wind energy applications.
• Multi-Element Alloy Co-Permeation — Zinc-aluminum-rare earth alloy layer offering 2-3x the corrosion resistance of traditional galvanizing. Features self-healing properties at scratch points, ensuring long-term protection even in damaged areas. Ideal for critical infrastructure, power transmission towers, coastal projects, and marine installations.

Key Features

• Highest strength structural bolt — 150 ksi minimum tensile strength
• Quenched and tempered alloy steel for superior toughness and ductility
• Type 3 weathering steel for atmospheric corrosion resistance without coating
• NOT galvanized per ASTM A490 (hydrogen embrittlement risk) — Dacromet available as alternative
• Designed for use with ASTM F436 hardened washers and ASTM A563 DH heavy hex nuts
• Full RCSC compliance with pre-tensioning certification and installation records

Applications

• Critical structural steel connections requiring maximum load capacity
• High-rise building seismic moment frame connections
• Long-span bridge and infrastructure construction
• Heavy industrial and petrochemical structural steel
• Stadium, arena, and architecturally exposed structural steel
• Seismic retrofit and structural reinforcement projects

Why Choose BoltNutsPlus?

• ISO 9001:2015 Certified Manufacturing — consistent quality you can trust on every batch
• 15+ Years of Export Experience — serving 40+ countries across 6 continents
• Full Traceability — material certificates (EN 10204 3.1) and comprehensive test reports included
• Custom Packaging & OEM/ODM — your brand identity, your specifications, our precision manufacturing
• Third-Party SGS / Bureau Veritas Inspection Available upon request
• 24-Hour Quote Response — same-day reply for urgent requirements; standard 24-hour turnaround