Views: 0 Author: Site Editor Publish Time: 2025-07-31 Origin: Site
A325 bolts and A490 bolts are the backbone of modern steel construction, yet critical differences in strength, corrosion resistance, and applications dictate where each should be used. As a leading fastener manufacturer, Panda Fastener breaks down these essential ASTM standards to help engineers and contractors make informed decisions.
| Property | ASTM A325 Bolts | ASTM A490 Bolts |
|---|---|---|
| Material | Medium carbon steel (e.g., 1045) | Alloy steel (quenched & tempered) |
| Tensile Strength | 120 ksi (min) | 150-173 ksi (min) |
| Yield Strength | 92 ksi (min) | 130 ksi (min) |
| Corrosion Protection | Hot-dip galvanizing common | Not recommended for HDG |
| Cost Factor | Lower (~20-30% savings) | Higher (premium strength) |
A325 Bolts:
Made from medium carbon steel (UNS G10450) or boron steel.
Heat-treated for uniform strength.
Ideal for general structural connections like beam-column joints.
A490 Bolts:
Forged from alloy steel (e.g., 4140/4142) with chromium/molybdenum.
Undergo rigorous quenching/tempering for ultra-high strength.
Used in seismic zones, heavy machinery, and high-stress connections.
Panda Fastener Insight: *Galvanizing A490 bolts risks hydrogen embrittlement. Use mechanical plating or specify A490 Type 3 (weathering steel) for corrosion-prone environments.*
Shear Capacity: A490 bolts offer 30% higher shear strength than A325 bolts.
Fatigue Resistance: A490 outperforms in dynamic-load structures (e.g., bridges).
Preload Requirements: A490 bolts require 40% higher installation torque.
In a 10-story steel frame, using A490 bolts instead of A325 bolts reduces bolt count by 25%, saving weight and labor – but material costs rise.
A325 Bolts: Compatible with hot-dip galvanizing (HDG), zinc-rich coatings.
A490 Bolts: HDG causes hydrogen cracking. Specify:
Type 1: Plain finish (indoor use)
Type 3: Weathering steel (outdoor exposure)
Panda Pro Tip: *For coastal infrastructure, pair A490 Type 3 bolts with our Dacromet® coating for 500+ hour salt-spray resistance.*
Use A325 Bolts For:
Commercial buildings
Moderate-load bridges
Non-seismic regions
Connections with slip-critical joints
Use A490 Bolts For:
Skyscrapers & seismic frames
Heavy industrial plants
Crane rails & mining equipment
Critical tension joints
A325 Bolts:
Turn-of-nut or calibrated wrench installation
Proof load testing: 85% of min tensile strength
A490 Bolts:
Direct tension indicators (DTIs) required
Proof load: 95% of min tensile strength
Failure Case: In 2018, improper tightening of A490 bolts caused a stadium canopy collapse. Always follow RCSC Specification for Structural Joints.
| Factor | A325 Bolts | A490 Bolts |
|---|---|---|
| Bolt Cost (per 100) | $220-$280 | $340-$450 |
| Labor Cost | Lower (easier install) | Higher (precision req.) |
| Lifecycle Value | 15-20 years (HDG) | 25-30+ years (Type 3) |
Engineer’s Rule: *For projects > 50,000 bolts, A325 saves upfront costs; for high-risk structures, A490’s performance justifies the premium.*
Rising Demand for A490: Growth in mega-projects (e.g., data centers, offshore wind) drives 12% annual A490 usage increase.
Panda’s Hybrid Solutions: Our A490CR bolts combine 150 ksi strength with ISO 12944 C5 corrosion resistance.
A325 bolts deliver cost-effective strength for most steel structures, while A490 bolts are indispensable for extreme loads and seismic resilience. As your partner, Panda Fastener provides:
Certified A325 bolts with custom coatings
Premium A490 bolts (Type 1/3) with batch traceability
Technical support for ASTM compliance
Contact Panda Fastener today for project-specific bolt recommendations and instant quoting.
