This property will depend on the material the fasteners are made from. It is more commonly expressed in textbooks and datasheets as Ultimate Tensile Strength (Stress) which is the Ultimate Tensile Load divided by the area it is spread over. However, measuring the Ultimate Tensile Load is more practical than measuring stress in most applications.
Why is Knowing Tensile Loads important for fasteners?
This property is crucial for threaded fasteners because they are usually connecting two key components together. In a lot of mechanical failures, the threaded fasteners fail first and initiate fractures. Hence, it is important to know when they might fail.
Ultimate Tensile Loads
for Metric Fasteners
Tables 1 and 2 below show the Ultimate Tensile Loads for standard metric bolts for both coarse and fine pitch threads. The values for the Ultimate Tensile Loads are based on the specifications provided in ISO 898 Part 1.
This standard lays out specifications for the mechanical and physical properties for metric threaded fasteners made from carbon and alloy steel tested within a temperature range of 10°C to 35°C.
Table 1. Minimum Ultimate Tensile Loads — ISO Metric Fine Thread
| Nominal Size | Pitch, mm (Fine) | Nominal Stress Area, mm2 | Minimum Tensile Load, N (Property Class 8.8) |
|---|---|---|---|
| M8 | 1.00 | 39.2 | 31360 |
| M10 | 1.00 | 64.5 | 49000 |
| M10 | 1.25 | 61.2 | 51600 |
| M12 | 1.25 | 92.1 | 70500 |
| M12 | 1.50 | 88.1 | 73700 |
| M14 | 1.50 | 125 | 100000 |
| M16 | 1.50 | 167 | 134000 |
| M18 | 1.50 | 216 | 179000 |
| M20 | 1.50 | 272 | 226000 |
| M22 | 1.50 | 333 | 276000 |
| M24 | 2.00 | 384 | 319000 |
| M27 | 2.00 | 496 | 412000 |
| M30 | 2.00 | 621 | 515000 |
| M33 | 2.00 | 761 | 632000 |
| M36 | 3.00 | 865 | 718000 |
| M39 | 3.00 | 1030 | 855000 |
Table 2. Minimum Ultimate Tensile Loads — ISO Metric Coarse Thread
| Nominal Bolt Size | Pitch, mm (Coarse) | Nominal stress area, mm2 | Minimal Ultimate Tensile Loads, N (Property classes 4.8 to 10.9) | ||||
|---|---|---|---|---|---|---|---|
| 4.8 | 5.8 | 6.8 | 8.8 | 10.9 | |||
| M3 | 0.50 | 5.03 | 2110 | 2620 | 3020 | 4020 | 5230 |
| M3.5 | 0.60 | 6.78 | 2850 | 3530 | 4070 | 5420 | 7050 |
| M4 | 0.70 | 8.78 | 3690 | 4570 | 5270 | 7020 | 9130 |
| M5 | 0.80 | 14.2 | 5960 | 7380 | 8520 | 11350 | 14800 |
| M6 | 1.00 | 20.1 | 8440 | 10400 | 12100 | 161000 | 20900 |
| M7 | 1.00 | 28.9 | 12100 | 15000 | 17300 | 231000 | 30100 |
| M8 | 1.25 | 36.6 | 15400 | 19000 | 22000 | 292000 | 38100 |
| M10 | 1.50 | 58 | 24400 | 30200 | 34800 | 464000 | 60300 |
| M12 | 1.75 | 84.3 | 35400 | 43800 | 50600 | 67400 | 87700 |
| M14 | 2.00 | 115 | 48300 | 59800 | 69000 | 92000 | 120000 |
| M16 | 2.00 | 157 | 65900 | 81600 | 94000 | 125000 | 163000 |
| M18 | 2.50 | 192 | 80600 | 99800 | 115000 | 159000 | 200000 |
| M20 | 2.50 | 245 | 103000 | 127000 | 147000 | 203000 | 250000 |
| M22 | 2.50 | 303 | 127000 | 158000 | 182000 | 252000 | 315000 |
| M24 | 3.00 | 353 | 148000 | 184000 | 212000 | 293000 | 367000 |
| M27 | 3.00 | 459 | 193000 | 239000 | 275000 | 381000 | 477000 |
| M30 | 3.50 | 561 | 236000 | 292000 | 337000 | 466000 | 583000 |
| M33 | 3.50 | 694 | 292000 | 361000 | 416000 | 576000 | 722000 |
| M36 | 4.00 | 817 | 343000 | 425000 | 490000 | 678000 | 850000 |
| M39 | 4.00 | 976 | 410000 | 508000 | 586000 | 810000 | 1020000 |
Ultimate Tensile Loads
For Imperial Fasteners
The minimum tensile loads for imperial threaded fasteners are based on the requirements set in the standard SAE J429. This standard covers the requirements for chemical and material properties for inch series bolts, studs and threaded fasteners made from steel.
Tables 3 and 4 show the minimum ultimate tensile loads for UNC (coarse) and UNF (fine) threads.
Table 3. Minimum Tensile Load for Imperial Bolts (UNC)
| Nominal Size (in) | Stress area (in2) | Minimum Tensile Load (kN) | |
|---|---|---|---|
| Grade 5 | Grade 8 | ||
| 1/4 – 20 | 0.0318 | 16.9 | 21.1 |
| 5/16 – 18 | 0.0524 | 28.0 | 34.9 |
| 3/8 – 16 | 0.0775 | 41.4 | 51.6 |
| 7/16 – 14 | 0.1063 | 56.9 | 70.7 |
| 1/2 – 13 | 0.1419 | 75.6 | 94.7 |
| 9/16 – 12 | 0.182 | 96.9 | 121.4 |
| 5/8 – 11 | 0.226 | 120.5 | 150.8 |
| 3/4 – 10 | 0.334 | 178.4 | 222.9 |
| 7/8 – 9 | 0.462 | 246.4 | 308.2 |
| 1 – 8 | 0.606 | 323.3 | 404.3 |
| 1 1/8 – 7 | 0.763 | 356.3 | 508.9 |
| 1 1/4 – 7 | 0.969 | 452.3 | 646.8 |
| 1 3/8 – 6 | 1.155 | 539.6 | 770.4 |
| 1 1/2 – 6 | 1.405 | 656.1 | 937.7 |
Table 4. Minimum Tensile Load for Imperial Bolts (UNF)
| Nominal Size (in) | Stress area (in2) | Minimum Tensile Load (kN) | |
|---|---|---|---|
| Grade 5 | Grade 8 | ||
| 1/4 – 28 | 0.0364 | 19.3 | 24.2 |
| 5/16 – 24 | 0.058 | 30.9 | 38.6 |
| 3/8 – 24 | 0.0878 | 46.7 | 58.7 |
| 7/16 – 20 | 0.1187 | 63.1 | 79.1 |
| 1/2 – 20 | 0.1599 | 85.4 | 106.7 |
| 9/16 – 18 | 0.203 | 108.5 | 135.2 |
| 5/8 – 18 | 0.256 | 136.5 | 170.8 |
| 3/4 – 16 | 0.373 | 199.2 | 249.1 |
| 7/8 – 14 | 0.509 | 271.7 | 339.8 |
| 1 – 12 | 0.663 | 354.0 | 442.1 |
| 1 1/8 – 12 | 0.856 | 400.0 | 571.1 |
| 1 1/4 – 12 | 1.073 | 501.3 | 716.1 |
| 1 3/8 – 12 | 1.315 | 614.2 | 877.1 |
| 1 1/2 – 12 | 1.581 | 738.4 | 1055.1 |
The data provided in this document is for general guidance only and should not be solely relied upon when working to stringent specifications. We recommend consulting with qualified experts regarding any technical queries. This may change without written notice
Version No: 230301
