SAE 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.
What Grade 5 / A449 is.
SAE J429 Grade 5 and ASTM A449 Type 1 describe the same product: a medium-carbon steel hex cap screw, bolt or stud, quenched and tempered to 120 ksi tensile in sizes to 1 in., 105 ksi over 1 to 1½ in., and 90 ksi over 1½ to 3 in. A449 is the ASTM version that carries the larger sizes and the chemistry and testing rules; Grade 5 is the automotive and machinery designation marked with three radial lines on the head.
We machine A449 and Grade 5 hex cap screws, bolts and studs from certified bar, have them quenched and tempered to the specification, and supply them plain, zinc plated or hot-dip galvanized with A563 Grade B or DH nuts.
Chemical composition.
| Element | Symbol | Min % | Max % |
|---|---|---|---|
| Carbon | C | 0.30 | 0.52 |
| Manganese | Mn | 0.60 | — |
| Phosphorus | P | — | 0.040 |
| Sulfur | S | — | 0.050 |
| Silicon | Si | 0.15 | 0.30 |
Values per ASTM A449-14 (2020) Table 1 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team. Boron, alloy and alloy-boron steels are also permitted with the same carbon range.
Mechanical properties.
| Grade / condition and size | Tensile strength, min (ksi) | Yield or proof, min (ksi) | Elongation, min (%) | Reduction of area, min (%) | Hardness |
|---|---|---|---|---|---|
| ¼ to 1 in. | 120 | 92 | 14 | 35 | 25–34 HRC |
| Over 1 to 1½ in. | 105 | 81 | 14 | 35 | 19–30 HRC |
| Over 1½ to 3 in. | 90 | 58 | 14 | 35 | 183–235 HBW |
Values per ASTM A449-14 (2020) Tables 3 and 6 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team. Full-size tensile and proof loads by thread size are in Tables 4 and 5 of the specification.
Specifications that apply.
How Grade 5 / A449 ships from Houston.
- Hex and heavy hex bolts and cap screws
- Studs and threaded rod
- Nuts and washers to match
- Machined specials to drawing
Grade 5 / A449 fasteners we make.
Every item is manufactured to your drawing or standard in Grade 5 / A449, imperial or metric, with an EN 10204 3.1 certificate.
What is a Grade 5 bolt?
Grade 5 is the SAE J429 designation for a medium-carbon steel bolt quenched and tempered to 120 ksi tensile, identified by three radial lines on the head. ASTM A449 covers the same product for the inch sizes to 3 in. and adds the chemistry, hardness and testing rules that a certificate needs, which is why industrial orders are normally written to A449 while the head marking remains the Grade 5 lines. The strength steps down above 1 in. because heavier sections cannot be hardened through in medium-carbon steel.
Grade 5 or A325?
The steel and strength are the same to 1 in. A325 (now ASTM F3125 Grade A325) is the structural bolt with a heavy hex head, short thread length and tighter controls for building connections. Grade 5 and A449 are general-purpose bolts and studs with standard hex heads and full thread lengths. Use A325 when the drawing or code says so; use A449 for machinery, supports and anything not covered by a structural code.
Testing, certification and marking
- Tensile, proof load and hardness tested per lot to ASTM F606
- Grade mark three radial lines or A449 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 Grade 5 / A449 jobs.
SAE 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.
ASTM F3125/F3125M Grade A325 · Type 1 and Type 3ASTM 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.
ISO 898-1 · ASTM F568M Class 8.8Property Class 8.8 Metric Bolts (ISO 898-1 / ASTM F568M)
The metric Grade 5: medium-carbon steel quenched and tempered to 830 MPa (120 ksi) tensile and 660 MPa yield — the general-purpose high-strength metric bolt, equivalent to A449 and A325.