| Tensile Strength (N/mm2) | Hardness Vickers | Hardness Brinell* | HRB | HRF | HRC | HRA |
|---|---|---|---|---|---|---|
| 770 | 240 | 228 | 98.1 | 114.3 | 20.3 | 60.7 |
| 785 | 245 | 233 | 21.3 | 61.2 | ||
| 800 | 250 | 238 | 99.5 | 115.1 | 22.2 | 61.6 |
| 820 | 255 | 242 | 23.1 | 62.0 | ||
| 835 | 260 | 247 | (101) | 24.0 | 62.4 | |
| 850 | 265 | 252 | 25.8 | 62.7 | ||
| 865 | 270 | 257 | (102) | 25.8 | 63.1 | |
| 880 | 275 | 261 | 26.4 | 63.5 | ||
| 900 | 208 | 266 | (104) | 27.1 | 63.8 | |
| 915 | 285 | 271 | 27.8 | 64.2 | ||
| 930 | 290 | 276 | (105) | 28.5 | 64.5 | |
| 950 | 295 | 280 | 29.2 | 64.8 | ||
| 965 | 300 | 285 | 29.8 | 65.2 | ||
| 995 | 310 | 295 | 31.0 | 65.8 | ||
| 1030 | 320 | 304 | 32.2 | 66.4 | ||
| 1060 | 330 | 314 | 33.3 | 67.0 | ||
| 1095 | 340 | 323 | 34.4 | 67.6 | ||
| 1125 | 350 | 333 | 35.5 | 68.1 | ||
| 1155 | 360 | 342 | 36.6 | 68.7 | ||
| 1190 | 370 | 352 | 37.7 | 69.2 | ||
| 1220 | 380 | 361 | 38.8 | 69.8 | ||
| 1255 | 390 | 371 | 39.8 | 70.3 | ||
| 1290 | 400 | 380 | 40.8 | 70.8 | ||
| 1320 | 410 | 390 | 41.8 | 71.4 | ||
| 1350 | 420 | 399 | 42.7 | 71.8 | ||
| 1385 | 430 | 409 | 43.6 | 72.3 | ||
| 1420 | 440 | 418 | 44.5 | 72.8 | ||
| 1455 | 450 | 428 | 45.3 | 73.3 | ||
| 1485 | 460 | 437 | 46.1 | 73.6 | ||
| 1520 | 470 | 447 | 46.9 | 74.1 | ||
| 1555 | 480 | (456) | 47.7 | 74.5 | ||
| 1595 | 490 | (466) | 48.4 | 74.8 | ||
| 1630 | 500 | (475) | 49.1 | 75.3 | ||
| 1665 | 510 | (485) | 49.8 | 75.7 | ||
| 1700 | 520 | (494) | 50.5 | 76.1 | ||
| 1740 | 530 | (504) | 51.1 | 76.4 | ||
| 1775 | 540 | (513) | 51.7 | 76.7 | ||
| 1810 | 550 | (523) | 52.3 | 77.0 | ||
| 1845 | 560 | (532) | 53.0 | 77.4 | ||
| 1880 | 570 | (542) | 53.6 | 77.8 | ||
| 1920 | 580 | (551) | 54.1 | 78.0 | ||
| 1955 | 590 | (561) | 54.7 | 78.4 | ||
| 1995 | 600 | (570) | 55.2 | 78.6 | ||
| 2030 | 610 | (580) | 55.7 | 78.9 | ||
| 2070 | 620 | (589) | 56.3 | 79.2 | ||
| 2105 | 630 | (599) | 56.5 | 79.5 | ||
| 2145 | 640 | (608) | 57.3 | 79.8 | ||
| 2180 | 650 | (618) | 58.7 | 80.0 | ||
| 660 | 58.3 | 80.3 | ||||
| 670 | 58.8 | 80.6 | ||||
| 680 | 59.2 | 80.8 | ||||
| 690 | 59.7 | 81.1 | ||||
| 700 | 60.1 | 81.3 | ||||
| 720 | 61.0 | 81.8 | ||||
| 740 | 61.8 | 82.2 | ||||
| 760 | 62.5 | 82.6 | ||||
| 780 | 63.3 | 83.0 | ||||
| 800 | 64.0 | 83.4 | ||||
| 820 | 64.7 | 83.8 | ||||
| 840 | 65.3 | 84.1 | ||||
| 860 | 65.9 | 84.4 | ||||
| 880 | 66.4 | 84.7 | ||||
| 900 | 67.0 | 85.0 | ||||
| 920 | 67.5 | 85.3 | ||||
| 940 | 68.8 | 85.6 |
| Ball Dia | Rockwell 'C' Readings | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| (mm) | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 |
| 3.175 | 6.1 | 5.7 | 5.4 | 5.1 | 4.8 | 4.5 | 4.2 | 4.0 | 3.8 | 3.6 | 3.4 |
| 3.968 | 5.6 | 5.3 | 5.0 | 4.7 | 4.4 | 4.1 | 3.8 | 3.6 | 3.4 | 3.2 | 3.0 |
| 4.762 | 5.1 | 4.7 | 4.3 | 4.0 | 3.8 | 3.6 | 3.4 | 3.2 | 3.0 | 2.8 | 2.5 |
| 5.562 | 4.6 | 4.3 | 4.0 | 3.7 | 3.5 | 3.3 | 3.1 | 2.9 | 2.7 | 2.5 | 2.3 |
| 6.350 | 4.1 | 3.8 | 3.6 | 3.3 | 3.1 | 2.9 | 2.7 | 2.5 | 2.3 | 2.1 | 1.8 |
| 7.000 | 3.7 | 3.4 | 3.2 | 3.0 | 2.8 | 2.6 | 2.4 | 2.2 | 2.0 | 1.8 | 1.6 |
| 7.938 | 3.1 | 2.9 | 2.7 | 2.6 | 2.4 | 2.2 | 2.0 | 1.9 | 1.7 | 1.5 | 1.3 |
| 8.000 | 3.1 | 2.9 | 2.7 | 2.6 | 2.4 | 2.2 | 2.0 | 1.9 | 1.7 | 1.5 | 1.3 |
| 9.000 | 2.7 | 2.5 | 2.4 | 2.2 | 2.0 | 1.9 | 1.7 | 1.5 | 1.4 | 1.2 | 1.1 |
| 9.525 | 2.5 | 2.3 | 2.2 | 2.0 | 1.9 | 1.8 | 1.6 | 1.4 | 1.2 | 1.1 | 1.0 |
| 10.000 | 2.4 | 2.2 | 2.0 | 1.9 | 1.8 | 1.7 | 1.5 | 1.3 | 1.1 | 1.0 | 0.9 |
| 11.000 | 2.1 | 2.0 | 1.8 | 1.7 | 1.6 | 1.5 | 1.3 | 1.1 | 0.9 | 0.8 | 0.7 |
| 12.000 | 1.9 | 1.7 | 1.6 | 1.5 | 1.4 | 1.3 | 1.1 | 1.0 | 0.8 | 0.7 | 0.6 |
| 12.700 | 1.8 | 1.7 | 1.6 | 1.5 | 1.4 | 1.2 | 1.0 | 0.9 | 0.7 | 0.6 | 0.5 |
| 13.000 | 1.8 | 1.7 | 1.6 | 1.5 | 1.4 | 1.2 | 1.0 | 0.9 | 0.7 | 0.6 | 0.5 |
| 14.000 | 1.6 | 1.5 | 1.4 | 1.3 | 1.2 | 1.0 | 0.9 | 0.8 | 0.6 | 0.5 | 0.4 |
| 15.000 | 1.5 | 1.4 | 1.3 | 1.2 | 1.1 | 0.9 | 0.8 | 0.7 | 0.5 | 0.4 | 0.3 |
| 15.875 | 1.4 | 1.3 | 1.2 | 1.1 | 1.0 | 0.9 | 0.8 | 0.7 | 0.5 | 0.4 | 0.3 |
This table is useful for converting Rockwell 'C' readings taken on ball surfaces to equivalent value applicable to flat surfaces. Hardness readings of balls are affected by the curvature and hardness level of the ball. Because of these factors, corrections are necessarily added to the as-read hardness. For ball sizes and hardness values other than shown, values shall be interpolated.
