Grades stocked: BC · BD
Scope
ASTM A354 covers quenched-and-tempered alloy steel bolts, studs, and externally threaded fasteners in inch diameters from 1/4" through 4". Two grades differentiated by tensile strength cover the range from heavy mechanical duty to the highest-strength bolting commonly available outside of aerospace-specific specifications.
A354 is a high-strength alloy spec without the narrow-purpose focus of A193 (pressure/temp) or F3125 (structural connections). When designers need raw bolt strength in sizes or applications that fall outside structural steel fabrication, A354 is the typical answer.
Grades
| Grade | Min. Tensile | Min. Yield | Typical use |
|---|---|---|---|
| BC | 125 ksi | 109 ksi (≤2-1/2") | Heavy mechanical; comparable strength class to A449 |
| BD | 150 ksi | 130 ksi (≤2-1/2") | High-strength structural; anchor rods beyond F1554 Grade 105 |
Mechanical properties — Grade BC
| Diameter | Min. Tensile | Min. Yield | Min. Elong. | Min. RA | Max. Hardness |
|---|---|---|---|---|---|
| Up to 2-1/2" | 125 ksi | 109 ksi | 16% | 50% | 35 HRC |
| Over 2-1/2" through 4" | 115 ksi | 99 ksi | 16% | 45% | 35 HRC |
Mechanical properties — Grade BD
| Diameter | Min. Tensile | Min. Yield | Min. Elong. | Min. RA | Hardness Range |
|---|---|---|---|---|---|
| Up to 2-1/2" | 150 ksi | 130 ksi | 14% | 40% | 33–39 HRC |
| Over 2-1/2" through 4" | 140 ksi | 115 ksi | 14% | 40% | 31–39 HRC |
Grade BD carries both a minimum and maximum hardness, unlike most A-series bolt specs. The upper hardness limit protects against hydrogen embrittlement susceptibility at very high strength levels.
Chemistry
A354 is alloy steel, typically AISI 4140 or 4340 family, with heat-treatment to develop the specified strength:
- Carbon, manganese, phosphorus, sulfur, silicon to commercial limits
- At least one alloy addition from chromium, nickel, molybdenum, vanadium, or boron
- Quenched and tempered to achieve tensile, yield, and hardness targets
Recommended nuts and washers
| Bolt | Nut | Washer |
|---|---|---|
| BC | A563 Grade C or DH heavy hex; A194 2H acceptable | F436 or F844 |
| BD | A563 DH heavy hex; A194 2H acceptable | F436 hardened required for pretensioned service |
For tensioned connections where bolt load is a design input, F436 hardened washers under the turned element are required to prevent embedment into mating steel.
Hot-dip galvanizing and hydrogen embrittlement
Grade BD is susceptible to hydrogen embrittlement at its high strength level. When HDG is specified on Grade BD:
- Acid pickling chemistry and time must be controlled
- Post-galvanizing baking to relieve absorbed hydrogen is required
- Mechanical galvanizing per B695 is often preferred as a lower-risk alternative
- Some specifications prohibit HDG on Grade BD entirely — check the project spec
Grade BC (at 125 ksi tensile) is less susceptible and galvanizes more straightforwardly, but the same controls apply.
Applications
Grade BC
- Heavy equipment foundations
- Machinery assembly where A449 isn't heavy enough
- Generic high-strength alloy rod stock
Grade BD
- Large-diameter anchor bolts above F1554 Grade 105 capacity
- Dam gates and hydroelectric equipment
- Heavy crane and rigging hardware
- Large-diameter flange bolting outside pressure/temp service (where A193 doesn't fit)
- Wind tower anchor rods in some specifications
- Bridge expansion joints and heavy mechanical assemblies
A354 vs neighboring specs
| Spec | Grade | Tensile | Use |
|---|---|---|---|
| A449 | — | 120/105/90 ksi (size-dependent) | General Q&T, widely available |
| A354 BC | BC | 125 ksi | Heavy mechanical |
| F1554 | 105 | 125 ksi | Anchor bolts in concrete |
| A354 BD | BD | 150 ksi | Highest-strength common carbon bolt |
| F3125 A490 | A490 | 150 ksi | Structural steel connections only |
The line between A354 BD and F3125 A490: both are 150 ksi, but F3125 A490 is only for structural steel connections per AISC / RCSC, while A354 BD is the general-application 150 ksi alloy bolt.
Marking
- Grade BC: "BC" plus manufacturer's mark
- Grade BD: "BD" plus manufacturer's mark; three radial lines are an older convention sometimes still seen
Related specifications
- A449 — Lighter-duty Q&T alternative
- F1554 Grade 105 — Anchor bolt alternative at similar tensile to BC
- F3125 A490 — Structural-only alternative at BD tensile
- A563 — Nuts (Grade DH pairs with BD; Grade C with BC)
- A194 — 2H nuts (acceptable substitute on BC and BD)
- F436 — Hardened washers (required on pretensioned BD)
- B695 — Mechanical galvanizing (alternative to HDG on Grade BD)
Documentation
California Fastener A354 orders ship with mill certificates showing grade, heat number, chemistry, mechanical properties (tensile, yield, elongation, reduction of area), and hardness test results. Grade BD orders include tempering temperature records to support hydrogen embrittlement assessment when coating is specified.