ASTM F3125 Grade A325 Structural Bolts (120 ksi)
The structural steel connection bolt: heavy hex head, 120 ksi tensile, ½ to 1½ in., quenched and tempered, with the twist-off F1852 and metric A325M variants in the same specification.
What A325 (F3125) is.
ASTM F3125 consolidated the old A325, A490, F1852 and F2280 specifications. Grade A325 is the 120 ksi heavy hex structural bolt used in bolted steel connections, in Type 1 (plain carbon, boron or alloy steel) and Type 3 (weathering steel). It is limited to ½ through 1½ in., has a short thread length so the shank is in the shear plane, and is supplied with A563 DH nuts and F436 washers as a matched assembly.
We machine A325 bolts in the sizes and lengths that are hard to find, and supply them galvanized or plain with matching nuts and washers, marked A325 with the manufacturer's identifier.
Chemical composition.
| Element | Symbol | Min % | Max % |
|---|---|---|---|
| Carbon | C | 0.30 | 0.52 |
| Manganese | Mn | 0.60 | — |
| Phosphorus | P | — | 0.035 |
| Sulfur | S | — | 0.040 |
| Silicon | Si | 0.15 | 0.30 |
| Boron | B | — | 0.003 |
Values per ASTM F3125/F3125M-23 Table 3 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team. Type 3 weathering steel compositions are given separately in the same table.
Mechanical properties.
| Grade / condition and size | Tensile strength, min (ksi) | Yield or proof, min (ksi) | Elongation, min (%) | Reduction of area, min (%) | Hardness |
|---|---|---|---|---|---|
| A325 / F1852 — ½ to 1½ in. | 120 | 85 proof (92 by yield method) | — | — | 25–34 HRC (253–319 HBW) |
Values per ASTM F3125/F3125M-23 Tables 5 and 7 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team. Loads per thread size are listed in Table 5; the stress basis is shown here.
Specifications that apply.
How A325 (F3125) ships from Houston.
- Hex and heavy hex bolts and cap screws
- Studs and threaded rod
- Nuts and washers to match
- Machined specials to drawing
A325 (F3125) fasteners we make.
Every item is manufactured to your drawing or standard in A325 (F3125), imperial or metric, with an EN 10204 3.1 certificate.
What is an A325 bolt?
A325 is the workhorse structural bolt of North American steel construction: 120 ksi tensile, a heavy hex head for a big bearing face, and a short thread so that the unthreaded shank sits in the shear plane of a connection. Since 2015 it has lived in ASTM F3125 alongside A490 and the twist-off equivalents, but the head marking and the design values are unchanged. Type 1 is plain carbon or alloy steel and may be galvanized; Type 3 is weathering steel for unpainted structures.
Testing, certification and marking
- Tensile, proof load and hardness tested per lot to ASTM F606
- Grade mark A325 (Type 3 may carry an additional distinguishing mark at the manufacturer's option) and manufacturer's identification on the head or one end
- Certificate of conformance or test report with heat number on request; EN 10204 3.1 available
- Coating thickness reported when plated or galvanized
Recent A325 (F3125) jobs.
ASTM F3125 Grade A490 Structural Bolts (150 ksi)
The high-strength structural bolt: alloy steel, 150 to 173 ksi tensile, ½ to 1½ in., never hot-dip galvanized — with the twist-off F2280 and metric A490M variants in the same specification.
ASTM A449 Type 1 · SAE J429 Grade 5SAE Grade 5 / ASTM A449 Bolts (120 ksi)
The everyday high-strength bolt: quenched and tempered medium-carbon steel at 120 ksi to 1 in., stepping down for larger sizes — Grade 5 in SAE terms, A449 in ASTM terms.
ASTM A563 / A563MASTM A563 Carbon and Alloy Steel Nuts (Grades A, B, C, D, DH, DH3)
The nut specification for carbon and alloy steel bolting: Grade A for A307, Grade B for cast-iron flanges, C and D for 105 to 120 ksi bolts, and DH and DH3 heat treated for A325, A490, A354 and Grade 8 — with proof stress by grade and style.