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.
What Grade 8 / A354 BD is.
SAE J429 Grade 8 and ASTM A354 Grade BD describe the same class of product: an alloy steel bolt or stud quenched and tempered to 150 ksi tensile and 130 ksi yield, at 33 to 38 HRC. Grade 8 is marked with six radial lines and runs to 1½ in.; A354 BD covers sizes to 4 in. with a nickel-chromium-molybdenum requirement above 2¼ in. and is the specification industrial and structural orders are written to.
We machine A354 BD and Grade 8 bolts, cap screws and studs from certified 4140, 4340 and equivalent bar, have them quenched and tempered to the specification, and supply them plain, zinc plated with a hydrogen relief bake, or zinc-flake coated, with A563 Grade DH nuts.
Chemical composition.
| Element | Symbol | Min % | Max % |
|---|---|---|---|
| Carbon | C | 0.30 | 0.53 |
| Manganese | Mn | 0.60 | — |
| Phosphorus | P | — | 0.035 |
| Sulfur | S | — | 0.040 |
| Boron | B | — | 0.003 |
| Alloying elements | — | per F1789 alloy definition | — |
Values per ASTM A354-17 Table 1 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team. Grade BD over 2¼ in. requires carbon 0.35–0.53 % and 0.40 % Ni, 0.40 % Cr and 0.15 % Mo minimum.
Mechanical properties.
| Grade / condition and size | Tensile strength, min (ksi) | Yield or proof, min (ksi) | Elongation, min (%) | Reduction of area, min (%) | Hardness |
|---|---|---|---|---|---|
| Grade BD — all sizes to 4 in. | 150 (173 max) | 130 | 14 | 40 | 33–38 HRC (311–352 HBW) |
Values per ASTM A354-17 Tables 2 and 4 (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 Table 3 of the specification.
Specifications that apply.
How Grade 8 / A354 BD 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 8 / A354 BD fasteners we make.
Every item is manufactured to your drawing or standard in Grade 8 / A354 BD, imperial or metric, with an EN 10204 3.1 certificate.
What is a Grade 8 bolt?
Grade 8 is the SAE J429 designation for an alloy steel bolt quenched and tempered to 150 ksi tensile, marked with six radial lines. ASTM A354 Grade BD is the industrial specification for the same strength, extending to 4 in. diameter and adding the alloy chemistry, hardness range and full-size test loads that certification requires. Both are made from medium-carbon alloy steels such as 4140 and 4340, hardened through the section and tempered to 33 to 38 HRC.
Grade 8 or A490?
Same strength, different job. A490 (ASTM F3125) is the structural bolt with a heavy hex head and short thread for steel connections, limited to 1½ in. A354 BD is the general-purpose 150 ksi bolt and stud, and the material many codes allow for structural anchor and connection bolting above 1½ in. where A490 is not available.
Plating high-strength bolts
At 33 to 38 HRC Grade 8 and BD are susceptible to hydrogen embrittlement after electroplating. Every plated lot is baked within hours of plating, or zinc-flake coating is supplied instead, which puts no hydrogen into the steel during coating.
Testing, certification and marking
- Tensile, proof load and hardness tested per lot to ASTM F606
- Grade mark six radial lines or BD 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 8 / A354 BD jobs.
ASTM A354 Grade BC Bolts (125 ksi)
Alloy steel bolting between Grade 5 and Grade 8: 125 ksi tensile and 109 ksi yield in sizes to 2½ in., 115 ksi above — the anchor-bolt and large-stud grade that holds its strength in big diameters.
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 F3125/F3125M Grade A490 · Type 1 and Type 3ASTM 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.