ASTM A540 Grade B24 is a high tensile alloy steel bolting grade intended for special application such as nuclear power plant installations. Grade B24 Bolts are available in 5 different tensile class namely 5,4,3,2 &1 depending upon the diameter of the bolts. A540 Grade B24 bolts are manufactured from Chromium Nickel Vanadium (Cr-Ni-V) Steel (AISI 4340-H) with tensile ranging from 115 ksi to 165 ksi (inch-pound) & 790MPa to 1140 Mpa. These bolts need to undergo charpy v notch impact test as compulsory requirement. Ferrobend can produce these bolting from 1/2 inch through 9-1/2 inch with EN 10204 Type 3.1 Certification
| Grade B24 | Class 5 | Class 4 | Class 3 | Class 2 | Class 1 |
| Element | ||||
|---|---|---|---|---|
| Grade B24 | ||||
| 4340-Mod. | ||||
| Chrome Nickel Vanadium | ||||
| RangeB, % | ||||
| Carbon | 0.37 - 0.44 | |||
| Manganese | 0.70 - 0.90 | |||
| PhosphorusC, max | 0.025 | |||
| SulfurC, max | 0.025 | |||
| Silicon | 0.15 - 0.35 | |||
| Chromium | 0.70 - 0.95 | |||
| Nickel | 1.65 - 2.00 | |||
| Molybdenum | 0.30 - 0.40 | |||
| Vanadium | --- | |||
A The intensional addition of Bi, Se, Te and Pb is not permitted.
B Unless otherwise specified, separate determinations may vary from the specified ranges, except that elements in any heat mush not vary both above and below the specified range.
C Phosphorus and sulfur content is 0.04% max when open hearth steel is specified.
D Silicon content is 0.35& mac if vacuum carbon deoxidized.
| Grades | Class | Diameter, inch. | Tensile Strength, min | Yield Strength, 0.2% offset, min |
Elongation min, % |
Reduction of Area, min, % |
Surface Brinell Hardness |
Charpy V Notch +10 °F [-12.2 °C] | |
|---|---|---|---|---|---|---|---|---|---|
| Inch Pound Units | |||||||||
| ksi | ksi | In 2 inch. | Min | Max | |||||
| Grade B24 (4340 Mod.) | 5 | to 6, incl. | 120 | 105 | 15 | 50 | 248 | 311 | A |
| 5 | over 6 to 8, incl. | 115 | 100 | 15 | 50 | 255 | 321 | A | |
| 5 | over 8 to 9-1/2, incl. | 115 | 100 | 15 | 50 | 262 | 321 | A | |
| 4 | to 3, incl. | 135 | 120 | 13 | 45 | 269 | 341 | A | |
| 4 | over 3 to 6, incl. | 135 | 120 | 13 | 45 | 277 | 352 | A | |
| 4 | over 6 to 8, incl. | 135 | 120 | 13 | 45 | 285 | 363 | A | |
| 4 | over 8 to 9-1/2, incl. | 135 | 120 | 13 | 45 | 293 | 363 | D | |
| 3 | to 3, incl. | 145 | 130 | 12 | 40 | 293 | 363 | B | |
| 3 | over 3 to 8, incl. | 145 | 130 | 12 | 40 | 302 | 388 | B | |
| 3 | over 8 to 9-1/2, incl. | 145 | 130 | 12 | 40 | 311 | 388 | D | |
| 2 | to 7, incl. | 155 | 140 | 11 | 40 | 311 | 401 | B | |
| 2 | over 7 to 9-1/2, incl. | 155 | 140 | 11 | 40 | 321 | 415 | D | |
| 1 | to 6, incl. | 165 | 150 | 10 | 35 | 321 | 415 | C | |
| 1 | over 6 to 8, incl. | 165 | 150 | 10 | 35 | 331 | 429 | D | |
| Grades | Class | Diameter, mm. | Tensile Strength, min | Yield Strength, 0.2% offset, min |
Elongation min, % |
Reduction of Area, min, % |
Surface Brinell Hardness |
Charpy V Notch +10 °F [-12.2 °C] | |
|---|---|---|---|---|---|---|---|---|---|
| Metric Units | |||||||||
| Mpa | Mpa | In 50 mm | Min | Max | |||||
| Grade B24 (4340 Mod.) | 5 | to 50, incl. | 825 | 725 | 15 | 50 | 248 | 311 | A |
| 5 | over 150 to 200, incl. | 795 | 690 | 15 | 50 | 255 | 321 | A | |
| 5 | over 200 to 240,, incl. | 795 | 690 | 15 | 50 | 262 | 321 | A | |
| 4 | to 75, incl. | 930 | 825 | 13 | 45 | 269 | 341 | A | |
| 4 | over 75 to 150, incl. | 930 | 825 | 13 | 45 | 277 | 352 | A | |
| 4 | over 150 to 200, incl. | 930 | 825 | 13 | 45 | 285 | 363 | A | |
| 4 | over 200 to 240, incl. | 930 | 825 | 13 | 45 | 293 | 363 | D | |
| 3 | to 75, incl. | 1000 | 895 | 12 | 40 | 293 | 363 | B | |
| 3 | over 75 to 200, incl. | 1000 | 895 | 12 | 40 | 302 | 388 | B | |
| 3 | over 200 to 240, incl. | 1000 | 895 | 12 | 40 | 311 | 388 | D | |
| 2 | to 180, incl. | 1070 | 965 | 11 | 40 | 311 | 401 | B | |
| 2 | over 180 to 240, incl. | 1070 | 965 | 11 | 40 | 321 | 415 | D | |
| 1 | to 150, incl. | 1140 | 1035 | 10 | 35 | 321 | 415 | C | |
| 1 | over 150 to 200, incl. | 1140 | 1035 | 10 | 35 | 331 | 429 | D | |
Note A : The minimum average of 3 specimens shall not be less than 35ft-lbf (47 J). One specimen from a set of 3 may be less than 35 ft-lbf (47 J) but not less than 30 ft-lbf (41J).
Note B : The minimum average of 3 specimens shall not be less than 30ft-lbf (41 J). One specimen from a set of 3 may be less than 30 ft-lbf (41 J) but not less than 25 ft-lbf (34J).
Note C : The minimum average of 3 specimens shall not be less than 25ft-lbf (34 J). One specimen from a set of 3 may be less than 25 ft-lbf (34 J) but not less than 20 ft-lbf (27J).
Note D : No minimum values established. Tests shall be run for information only.
Bolting material ordered in the annealed condition shall have a structure suitable for machining. Such annealed material is not intended to be used without subsequent quenching and tempering. Bolting ordered in the liquid quenched and tempered condition shall be uniformly reheated froma temperature below the cooling transformation range to the proper austenitizing temperature, quenched in a liquid medium under substantially uniform conditions, and then uniformly reheated for tempering. The minimum tempering tempereture shall be 850°F [455°C].
Material that has been straintened after quenching and tempering shall be stress relieved by reheating to a temperature not lower than 100°F [55°C] under the tempering temperature.
The hardness shall be determined on the surface of the material removal of decarburization. The hardness of material in the annealed condition shall not be greater than 235 HB. The hardness of material in the quenched and tempered or quenched, temepred and stress-relieved condition shall be within the limits in hardness column of the mechanical properties table.
| Grade | Marking |
|---|---|
| Grade B24 Class 1 | B24-1 BPF |
| Grade B24 Class 2 | B24-2 BPF |
| Grade B24 Class 3 | B24-3 BPF |
| Grade B24 Class 4 | B24-4 BPF |
| Grade B24 Class 5 | B24-5 BPF |