APPROXIMATE ROCKWELL HARDNESS CONVERSION NUMBERS FOR
AUSTENITIC SHEET STEEL
Rockwell Hardness Number |
Rockwell Superficial Hardness Number |
|||
| C Scale, 150-kgf Diamond Penetrator (HRC) |
A Scale, 60-kgf Diamond Penetrator (HRA) |
15-N Scale, 15-kgf Superficial Diamond Penetrator (HR 15-N) |
30-N Scale, 30-kgf Superficial Diamond Penetrator (HR 30-N) |
45-N Scale, 45-kgf Superficial Diamond Penetrator (HR 45-N) |
| 48 | 74.4 | 84.1 | 66.2 | 52.1 |
| 47 | 73.9 | 83.6 | 65.3 | 50.9 |
| 46 | 73.4 | 83.1 | 64.5 | 49.8 |
| 45 | 72.9 | 82.6 | 63.6 | 48.7 |
| 44 | 72.4 | 82.1 | 62.7 | 47.5 |
| 43 | 71.9 | 81.6 | 61.8 | 46.4 |
| 42 | 71.4 | 81.0 | 61.0 | 45.2 |
| 41 | 70.9 | 80.5 | 60.1 | 44.1 |
| 40 | 70.4 | 80.0 | 59.2 | 43.0 |
| 39 | 69.9 | 79.5 | 58.4 | 41.8 |
| 38 | 69.3 | 79.0 | 57.5 | 40.7 |
| 37 | 68.8 | 78.5 | 56.6 | 39.6 |
| 36 | 68.3 | 78.0 | 55.7 | 38.4 |
| 35 | 67.8 | 77.5 | 54.9 | 37.3 |
| 34 | 67.3 | 77.0 | 54.0 | 36.1 |
| 33 | 66.8 | 76.5 | 53.1 | 35.0 |
| 32 | 66.3 | 75.9 | 52.3 | 33.9 |
| 31 | 65.8 | 75.4 | 51.4 | 32.7 |
| 30 | 65.3 | 74.9 | 50.5 | 31.6 |
| 29 | 64.8 | 74.4 | 49.6 | 30.4 |
| 28 | 64.3 | 73.9 | 48.8 | 29.3 |
| 27 | 63.8 | 73.4 | 47.9 | 28.2 |
| 26 | 63.3 | 72.9 | 47.0 | 27.0 |
| 25 | 62.8 | 72.4 | 46.2 | 25.9 |
| 24 | 62.3 | 71.9 | 45.3 | 24.8 |
| 23 | 61.8 | 71.3 | 44.4 | 23.6 |
| 22 | 61.3 | 70.8 | 43.5 | 22.5 |
| 21 | 60.8 | 70.3 | 42.7 | 21.3 |
| 20 | 60.3 | 69.8 | 41.8 | 20.2 |
| B Scale, 100-kgf, 1/16 in (1.588 mm) ball (HRB) |
A Scale, 60-kgf, Diamond Penetrator (HRA) |
15-T Scale, 15-kgf, 1/16 in (1.588 mm) ball (HR 15-T) |
30-T Scale, 30-kgf, 1/16 in (1.588 mm) ball (HR 30-T) |
45-T Scale, 45-kgf, 1/16 in (1.588 mm) ball (HR 45-T) |
| 100 | 61.5 | 91.5 | 80.4 | 70.2 |
| 99 | 60.9 | 91.2 | 79.7 | 69.2 |
| 98 | 60.3 | 90.8 | 79.0 | 68.2 |
| 97 | 59.7 | 90.4 | 78.3 | 67.2 |
| 96 | 59.1 | 90.1 | 77.7 | 66.1 |
| 95 | 58.5 | 89.7 | 77.0 | 65.1 |
| 94 | 58.0 | 89.3 | 76.3 | 64.1 |
| 93 | 57.4 | 88.9 | 75.6 | 63.1 |
| 92 | 56.8 | 88.6 | 74.9 | 62.1 |
| 91 | 56.2 | 88.2 | 74.2 | 61.1 |
| 90 | 55.6 | 87.8 | 73.5 | 60.1 |
| 89 | 55.0 | 87.5 | 72.8 | 59.0 |
| 88 | 54.5 | 87.1 | 72.1 | 58.0 |
| 87 | 53.9 | 86.7 | 71.4 | 57.0 |
| 86 | 53.3 | 86.4 | 70.7 | 56.0 |
| 85 | 52.7 | 86.0 | 70.0 | 55.0 |
| 84 | 52.1 | 85.6 | 69.3 | 54.0 |
| 83 | 51.5 | 85.2 | 68.6 | 52.9 |
| 82 | 50.9 | 84.9 | 67.9 | 51.9 |
| 81 | 50.4 | 84.5 | 67.2 | 50.9 |
| 80 | 49.8 | 84.1 | 66.5 | 49.9 |
| 79 | 49.2 | 83.8 | 65.8 | 48.9 |
| 78 | 48.6 | 83.4 | 65.1 | 47.9 |
| 77 | 48.0 | 83.0 | 64.4 | 46.8 |
| 76 | 47.4 | 82.6 | 63.7 | 45.8 |
| 75 | 46.9 | 82.3 | 63.0 | 44.8 |
| 74 | 46.3 | 81.9 | 62.4 | 43.8 |
| 73 | 45.7 | 81.5 | 61.7 | 42.6 |
| 72 | 45.1 | 81.2 | 61.0 | 41.8 |
| 71 | 44.5 | 80.8 | 60.3 | 40.7 |
| 70 | 43.9 | 80.4 | 59.6 | 39.7 |
| 69 | 43.3 | 80.1 | 58.9 | 38.7 |
| 68 | 42.8 | 79.7 | 58.2 | 37.7 |
| 67 | 42.2 | 79.3 | 57.5 | 36.7 |
| 66 | 41.6 | 78.9 | 56.8 | 35.7 |
| 65 | 41.0 | 78.6 | 56.1 | 34.7 |
| 64 | 40.4 | 78.2 | 55.4 | 33.6 |
| 63 | 39.8 | 77.8 | 54.7 | 32.6 |
| 62 | 39.3 | 77.5 | 54.0 | 31.6 |
| 61 | 38.7 | 77.1 | 53.3 | 30.6 |
| 60 | 38.1 | 76.7 | 52.6 | 29.6 |
| Standard deviation D | 1.44 | 2.29 | 1.67 | 1.57 |
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