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.
What A490 (F3125) is.
Grade A490 in ASTM F3125 is the 150 ksi structural bolt, made from quenched-and-tempered alloy steel at 33 to 38 HRC. It uses the same heavy hex head and short thread as A325 and the same ½ to 1½ in. size range, but carries 25 percent more load. Because of its hardness it must not be hot-dip galvanized; the zinc-aluminium coating under ASTM F3393 (which replaced F1136 and F2833) is the qualified coating, and plain bolts are supplied lightly oiled.
We machine A490 bolts in the sizes and lengths that are hard to find, and supply them with A563 DH nuts and F436 washers, marked A490 with the manufacturer's identifier.
Chemical composition.
| Element | Symbol | Min % | Max % |
|---|---|---|---|
| Carbon | C | 0.30 | 0.48 |
| Manganese | Mn | 0.60 | — |
| Phosphorus | P | — | 0.035 |
| Sulfur | S | — | 0.040 |
| 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. Carbon is 0.35–0.53 for 1½ in. bolts; alloying elements per the alloy steel definition.
Mechanical properties.
| Grade / condition and size | Tensile strength, min (ksi) | Yield or proof, min (ksi) | Elongation, min (%) | Reduction of area, min (%) | Hardness |
|---|---|---|---|---|---|
| A490 / F2280 — ½ to 1½ in. | 150 (173 max) | 120 proof (130 by yield method) | — | — | 33–38 HRC (311–352 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.
Specifications that apply.
How A490 (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
A490 (F3125) fasteners we make.
Every item is manufactured to your drawing or standard in A490 (F3125), imperial or metric, with an EN 10204 3.1 certificate.
What is an A490 bolt?
A490 is the 150 ksi structural bolt, the alloy-steel counterpart of A325. It carries the same head, thread and size range but is hardened to 33 to 38 HRC, which is why it must never be hot-dip galvanized: the acid pickling and the coating process charge hydrogen into hard steel and the bolt can crack in service days after installation. A490 also has a maximum tensile of 173 ksi so that it stays ductile enough for a bolted connection to yield rather than snap.
Testing, certification and marking
- Tensile, proof load and hardness tested per lot to ASTM F606
- Grade mark A490 (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
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.
ASTM A354 Grade BD · SAE J429 Grade 8SAE Grade 8 / ASTM A354 Grade BD Bolts (150 ksi)
The high-strength alloy bolt: quenched and tempered alloy steel at 150 ksi tensile and 130 ksi yield in all sizes to 4 in. — Grade 8 in SAE terms, A354 BD in ASTM terms.
ISO 898-1 · ASTM F568M Class 10.9Property Class 10.9 Metric Bolts (ISO 898-1 / ASTM F568M)
The metric Grade 8: alloy steel quenched and tempered to 1040 MPa (150 ksi) tensile and 940 MPa yield, 33 to 39 HRC — equivalent to A354 BD and A490 in the inch system.