Chemical composition as per ISO 898-2 for typical grades
| CLASS | MATERIAL AND TREATMENT | C MAX. | MN MIN. | P MAX. | S MAX. |
|---|---|---|---|---|---|
| 8 (M16 AND BELOW) | CARBON STEEL (MAY BE QUENCHED AND TEMPERED) | 0.58 | 0.25 | 0.060 | 0.150 |
| 8 (ABOVE M16) | CARBON STEEL QUENCHED AND TEMPERED | 0.58 | 0.30 | 0.048 | 0.058 |
| 10 | CARBON STEEL QUENCHED AND TEMPERED | 0.58 | 0.30 | 0.048 | 0.058 |
| 12 | CARBON STEEL QUENCHED AND TEMPERED | 0.58 | 0.45 | 0.048 | 0.058 |
Hardness requirement as per ISO 898-2 for typical grades
| HARDNESS SCALE | SIZE | CLASS 8 MIN. | CLASS 8 MAX. | CLASS 10 MIN. | CLASS 10 MAX. | CLASS 12 MIN. | CLASS 12 MAX. |
|---|---|---|---|---|---|---|---|
| VICKERS, HV | M5 TO M16 | 200 | 302 | 272 | 353 | 295 | 353 |
| ABOVE M16 TO M39 | 233 | 353 | 272 | ||||
| BRINELL, HB | M5 TO M16 | 190 | 287 | 259 | 336 | 280 | 336 |
| ABOVE M16 TO M39 | 221 | 336 | 259 | ||||
| ROCKWELL, HRC | M5 TO M16 | – | 30 | 26 | 36 | 29 | 36 |
ISO 898-2:2012 Mechanical properties of fasteners made of carbon steel and alloy steel -- Part 2: Nuts with specified property classes -- Coarse thread and fine pitch thread
