ASTM A193 Bolt Material Properties
Alloy Steel & Stainless Steel Bolting for High Temperature Service
About
ASTM A193 covers alloy steel and stainless steel bolting materials for pressure vessels, valves, flanges, and fittings for high temperature or high pressure service, or other special purpose applications. The table below contains data from Table 2 of ASTM A193/A193M, which lists the mechanical requirements for inch-series products.
Common grades include B7 (the most widely used grade for high-temperature service), B8 and B8M (stainless steel grades), and B16 (for higher temperature applications than B7).
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Mechanical Requirements Table
Use the grade filter below to look up mechanical properties for a specific bolt grade. Properties shown include minimum tensile strength, yield strength, elongation, reduction of area, maximum hardness, and minimum tempering temperature.
| Grade | Class | Diameter Range | Heat Treatment | Tensile (ksi) | Yield (ksi) | Elong. (%) | Red. of Area (%) | Hardness | Temper Temp (°F) |
|---|---|---|---|---|---|---|---|---|---|
| B5 | — | up to 4, incl | — | 100 | 80 | 16 | 50 | — | 1100 |
| B6 | — | up to 4, incl | — | 110 | 85 | 15 | 50 | — | 1100 |
| B6X | — | up to 4, incl | — | 90 | 70 | 16 | 50 | 26 HRC | 1100 |
| B7 | — | 2½ and under | — | 125 | 105 | 16 | 50 | 321 HB or 35 HRC | 1100 |
| B7 | — | over 2½ to 4 | — | 115 | 95 | 16 | 50 | 321 HB or 35 HRC | 1100 |
| B7 | — | over 4 to 7 | — | 100 | 75 | 18 | 50 | 321 HB or 35 HRC | 1100 |
| B7M | — | 4 and under | — | 100 | 80 | 18 | 50 | 235 HB or 99 HRB | 1150 |
| B7M | — | over 4 to 7 | — | 100 | 75 | 18 | 50 | 235 BHN or 99 HRB | 1150 |
| B16 | — | 2½ and under | — | 125 | 105 | 18 | 50 | 321 HB or 35 HRC | 1200 |
| B16 | — | over 2½ to 4 | — | 110 | 95 | 17 | 45 | 321 HB or 35 HRC | 1200 |
| B16 | — | over 4 to 8 | — | 100 | 85 | 16 | 45 | 321 HB or 35 HRC | 1200 |
| B8,B8M,B8P,B8LN,B8MLN | 1,1D | all diameters | carbide solution treated | 75 | 30 | 30 | 50 | 223 HB or 96 HRB | — |
| B8C,B8T | 1 | all diameters | carbide solution treated | 75 | 30 | 30 | 50 | 223 HB or 96 HRB | — |
| B8A,B8CA,B8MA,B8PA,B8TA,B8LNA,B8MLNA,B8NA,B8MNA,B8MLCuNA | 1A | all diameters | carbide solution treated in the finished condition | 75 | 30 | 30 | 50 | 192 HB or 90 HRB | — |
| B8N,B8MN,B8MLCuN | 1B,1D | all diameters | carbide solution treated | 80 | 35 | 30 | 40 | 223 HB or 96 HRB | — |
| B8R | 1C,1D | all diameters | carbide solution treated | 100 | 55 | 35 | 55 | 271 HB or 28 HRC | — |
| B8RA | 1C | all diameters | carbide solution treated in the finished condition | 100 | 55 | 35 | 55 | 271 HB or 28 HRC | — |
| B8S | 1C,1D | all diameters | carbide solution treated | 95 | 50 | 35 | 55 | 271 HB or 28 HRC | — |
| B8SA | 1C | all diameters | carbide solution treated in the finished condition | 95 | 50 | 35 | 55 | 271 HB or 28 HRC | — |
| B8,B8C,B8P,B8T,B8N | 2 | ¾ and under | carbide solution treated and strain hardened | 125 | 100 | 12 | 35 | 321 HB or 35 HRC | — |
| B8,B8C,B8P,B8T,B8N | 2 | over ¾ to 1, incl | carbide solution treated and strain hardened | 115 | 80 | 15 | 35 | 321 HB or 35 HRC | — |
| B8,B8C,B8P,B8T,B8N | 2 | over 1 to 1¼, incl | carbide solution treated and strain hardened | 105 | 65 | 20 | 35 | 321 HB or 35 HRC | — |
| B8,B8C,B8P,B8T,B8N | 2 | over 1¼ to 1½ , incl | carbide solution treated and strain hardened | 100 | 50 | 28 | 45 | 321 HB or 35 HRC | — |
| B8M,B8MN,B8MLCuN | 2 | ¾ and under | carbide solution treated and strain hardened | 110 | 95 | 15 | 45 | 321 HB or 35 HRC | — |
| B8M,B8MN,B8MLCuN | 2 | over ¾ to 1 incl | carbide solution treated and strain hardened | 100 | 80 | 20 | 45 | 321 HB or 35 HRC | — |
| B8M,B8MN,B8MLCuN | 2 | Over 1 to 1¼ , incl | carbide solution treated and strain hardened | 95 | 65 | 25 | 45 | 321 HB or 35 HRC | — |
| B8M,B8MN,B8MLCuN | 2 | over 1¼ to 1½ , incl | carbide solution treated and strain hardened | 90 | 50 | 30 | 45 | 321 HB or 35 HRC | — |
| B8,B8M2 | 2B | 2 and under | carbide solution treated and strain hardened | 95 | 75 | 25 | 40 | 321 HB or 35 HRC | — |
| B8,B8M2 | 2B | over 2 to 2½ incl | carbide solution treated and strain hardened | 90 | 65 | 30 | 40 | 321 HB or 35 HRC | — |
| B8,B8M2 | 2B | over 21⁄2 to 3 incl | carbide solution treated and strain hardened | 80 | 55 | 30 | 40 | 321 HB or 35 HRC | — |
| B8M3 | 2C | 2 and under | carbide solution treated and strain hardened | 85 | 65 | 30 | 60 | 321 HB or 35 HRC | — |
| B8M3 | 2C | over 2 | carbide solution treated and strain hardened | 85 | 60 | 30 | 60 | 321 HB or 35 HRC | — |
Data sourced from ASTM A193/A193M, Table 2 — Mechanical Requirements, Inch Products.
How to Use This Chart
To find the mechanical properties for a specific bolt, select the grade using the dropdown filter above. If a grade has multiple rows, the properties vary by diameter range — find the row that matches your bolt diameter.
Key columns explained:
- Tensile Strength (ksi) — the minimum ultimate tensile strength the bolt must achieve.
- Yield Strength (ksi) — the minimum stress at which the bolt begins to deform permanently (0.2% offset method).
- Elongation (%) — the minimum percentage the bolt can stretch before fracture, measured over 4 diameters.
- Hardness — the maximum allowable hardness (HB = Brinell, HRC = Rockwell C, HRB = Rockwell B).
Related References
- ASTM A320 — Low-temperature bolting material properties
- ASTM A453 — High-temperature special application bolting
- All Bolt Materials — Overview of all bolting material standards