ASTM F436 Hardened Structural Washers
Hardened steel washers per ASTM F436 — quenched-and-tempered, Type 1 carbon steel at HRC 38–45 or Type 3 weathering steel. Required with ASTM F3125 A325/A490 structural bolts; mandatory over slotted or oversized holes and with turn-of-nut tensioning.
Last updated: 2026-11
Specifications
The F436 washer is the load-bearing partner of a structural bolt. Quenched and tempered to a hardness far above ordinary washers — Type 1 carbon steel at HRC 38–45, with Type 3 weathering steel for weathering bolt assemblies — it is designed to be stronger than the yield strength of the bolt: the bolt stretches before the washer deforms. Structural standards require it in ASTM F3125 Grade A325 and A490 connections, with Type 1 or Type 3 matched to the bolt type. Its outer diameter is deliberately smaller than common flat washers so it fits clustered bolt patterns on steel plates without overlapping edges, and it is the mandatory washer over slotted or oversized holes and wherever turn-of-nut tensioning is used. Galvanized assemblies take correspondingly galvanized F436 washers. The one field rule that matters most: never substitute a plain unhardened washer where F436 is specified — it is the common field error, and the plain washer embeds under preload.
| Standard | ASTM F436 — hardened steel washers, inch series (F436M metric counterpart) |
|---|---|
| Material / hardness | Type 1 carbon steel, quenched and tempered, HRC 38–45; Type 3 weathering steel |
| Strength principle | Stronger than the bolt yield — the bolt stretches before the washer deforms |
| Required with | ASTM F3125 Grade A325 / A490 structural connections — Type 1 or Type 3 matching the bolt type |
| Mandatory cases | Slotted holes, oversized holes, and turn-of-nut tensioning requiring load distribution |
| Geometry | Smaller OD than common flat washers by design — fits clustered bolt patterns without overlapping edges |
| Finishes | Plain (oil-coated), mechanically galvanized, or hot-dip galvanized to match the bolt coating |
| Metric counterpart | Hardened washers per ISO 7093-1/7094 series; DIN 6916 in European structural practice |
| Bolt size | OD max (in) | OD min (in) | ID max (in) | ID min (in) | TH max (in) | TH min (in) |
|---|---|---|---|---|---|---|
| 1/2 | 1.094 | 1.031 | .562 | .531 | .177 | .097 |
| 5/8 | 1.344 | 1.281 | .719 | .687 | .177 | .122 |
| 3/4 | 1.500 | 1.438 | .843 | .812 | .177 | .122 |
| 7/8 | 1.781 | 1.719 | .969 | .938 | .177 | .136 |
| 1 | 2.031 | 1.969 | 1.156 | 1.125 | .177 | .136 |
Materials
- Carbon steel (Type 1)
- Weathering steel (Type 3)
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 F436 Hardened Structural Washers) 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 10,000 pieces. Stock items run 3–7 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
Can a plain flat washer be used where ASTM F436 is specified?
No. Substituting a plain unhardened washer where F436 is called for is the common field error, and it fails quietly: under the high preload of an A325/A490 connection the unhardened washer dishes and embeds, bleeding tension out of the joint. The F436 washer is heat-treated so the bolt yields before the washer deforms. If a drawing or specification names F436 — and structural standards name it for every A325/A490 connection, mandatorily over slotted and oversized holes — the hardened washer is part of the connection’s strength, not an optional extra.
What is the MOQ and lead time for this washer type?
The minimum order quantity is 10,000 pieces. Stock items ship in 3–7 days; non-stock items are confirmed at quotation. Common sizes in this washer type are widely stocked; confirm the exact schedule against quantity and size mix at quotation.
What should an RFQ for this washer type state?
State the standard designation (for example DIN 125 or ASTM F436), the nominal bolt size it must fit, material and hardness requirements, finish (plain, zinc-plated, or hot-dip galvanized where the assembly calls for it), required certificates such as a mill test report per EN 10204 3.1, and quantity per size — plus destination country.
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