ASTM F3125 Grade A325 Type 3 Structural Bolts
Weathering-steel heavy hex structural bolts per ASTM F3125 Grade A325 Type 3 — the A325 type that develops a protective patina under cyclic wet-dry exposure, for uncoated structural joints in weathering steel. Grade strength equals the A325 line: 120,000 psi min tensile through 1 inch.
Last updated: 2026-11
Specifications
Type 3 is A325 re-made in weathering steel: same heavy hex structural bolt form, same grade-level strength (120,000 psi minimum tensile through 1 inch, 105,000 above), but a chemistry that corrodes differently. Under cyclic wet-dry atmospheric exposure it develops a dense protective patina, which is the whole point — the joint is left uncoated by design, matching weathering-steel members (ASTM A588 bridges and structures) where paint would only delay and disguise the patina the steel is chosen for. The trade is corrosion behavior for coating freedom: unlike Type 1, Type 3 is not the galvanizing choice — it is specified precisely where no coating is wanted. Order it when the drawing names Type 3 or when the joint is uncoated weathering steel; strength-wise it carries the same A325 design values the engineer already tabulated.
| Standard | ASTM F3125 Grade A325 Type 3 — heavy hex structural bolt in weathering steel |
|---|---|
| Material | Weathering steel — develops a protective patina under cyclic wet-dry atmospheric exposure |
| Tensile strength, min (grade) | 120,000 psi (≤ 1 in dia); 105,000 psi (> 1 in dia) — A325 grade line |
| Corrosion behavior | Uncoated service by design; patina forms and stabilizes with wet-dry cycling |
| Finish | Plain (uncoated); not the galvanizing choice — coated joints take Type 1 |
| Typical applications | Uncoated structural steel joints in weathering-steel bridges and structures (A588-type members) |
Materials
- Weathering steel
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (ASTM F3125 Grade A325 Type 3 Structural Bolts) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 1,000–10,000 pieces depending on size. Stock items run 3–7 days. High-strength and custom parts run 15–25 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
Is A325 Type 3 stronger than Type 1?
No — the difference is corrosion behavior, not strength. Both types sit in the same A325 grade: 120,000 psi minimum tensile through 1 inch diameter and 105,000 psi above it. Type 3 is weathering steel chosen so the uncoated joint forms its own protective patina; Type 1 is medium carbon steel chosen where the joint is coated or galvanized. Select by joint environment and coating system, and never mix Type 3 bolts into a painted Type 1 joint or vice versa — the mark on the head tells the inspector which is which.
What is the MOQ and lead time for this bolt grade?
The minimum order quantity is 1,000–10,000 pieces depending on size. Stock items ship in 3–7 days; high-strength and custom parts in 15–25 days. Common diameters in this grade are widely stocked; confirm the exact schedule against quantity and size mix at quotation.
What should an RFQ for this bolt grade state?
State the standard and grade (for example ISO 4017 Class 8.8 or ASTM F3125 Grade A325 Type 1), diameter and length, thread type (metric coarse or UNC/UNF), finish (plain, zinc, or hot-dip galvanized where the grade permits), required certificates such as a mill test report per EN 10204 3.1, and quantity per size — plus destination country.
Related knowledge
- What Bolt Property Classes 8.8, 10.9 and 12.9 Encode — and When High Strength Stops Being the Right Choice
- Bolt Grade Selection: ISO 898-1 8.8/10.9/12.9 vs ASTM A307 and A325
- 8.8 vs 10.9 vs 12.9 Bolts: Strength, Hardness and Cost — What the Evidence Settles
- Calculating Bolt Preload and Clamp Force: Torque, Friction and Tightening Method
- How to Determine Tightening Torque and Choose a Tightening Method for a Bolted Joint
- Fastener Failure Modes: Which Fatigue, Creep and SCC Controls the Evidence Supports
- Hydrogen Embrittlement in High-Strength Bolts: Which Grades Need Controls, Which Coatings and Baking Schedules Are Acceptable, and What to Require Before the RFQ
- Bolt Head Markings: What the Lines, Numbers and Letters Claim — and How to Verify the Grade Before Accepting a Lot
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support