Hardness Conversion Charts
Tensile Strength and Hardness Conversions for Steels
| Brinell Dia of Impression mm | Brinell Hardness Number HB | Vickers Hardness Number HV | Rockwell C Scale Hardness Number HRC | Equiv. Rm tonf/in2 | Equiv. Rmkgf/mm2 | Equiv. Rm N/mm2 |
|---|---|---|---|---|---|---|
| 832 | 65 | |||||
| 800 | 64 | |||||
| 772 | 63 | |||||
| 746 | 62 | |||||
| 697 | 60 | |||||
| 674 | 59 | |||||
| 653 | 58 | |||||
| 2.50 | (601) | 633 | 57 | |||
| 2.55 | (578) | 615 | 56 | |||
| 2.60 | (555) | 591 | 54.5 | |||
| 2.65 | (534) | 569 | 53.5 | |||
| 2.70 | (514) | 547 | 52 | |||
| 2.75 | (495) | 528 | 51 | |||
| 2.80 | (477) | 508 | 49.5 | |||
| 2.85 | (461) | 491 | 48.5 | 101 | 160 | 1569 |
| 2.90 | 444 | 474 | 47 | 98 | 155 | 1520 |
| 2.95 | 429 | 455 | 45.5 | 95 | 150 | 1471 |
| 3.00 | 415 | 440 | 44.5 | 92 | 145 | 1422 |
| 3.05 | 401 | 425 | 43 | 88 | 139 | 1363 |
| 3.10 | 388 | 410 | 42 | 85 | 134 | 1314 |
| 3.15 | 375 | 396 | 40.5 | 82 | 129 | 1265 |
| 3.20 | 363 | 383 | 39 | 80 | 126 | 1236 |
| 3.25 | 352 | 372 | 38 | 77 | 121 | 1187 |
| 3.30 | 341 | 360 | 36.5 | 75 | 118 | 1157 |
| 3.35 | 331 | 350 | 35.5 | 73 | 114 | 1118 |
| 3.40 | 321 | 339 | 34.5 | 71 | 111 | 1089 |
| 3.45 | 311 | 328 | 33 | 68 | 107 | 1049 |
| 3.50 | 302 | 319 | 32 | 66 | 104 | 1020 |
| 3.55 | 293 | 309 | 31 | 64 | 101 | 990 |
| 3.60 | 285 | 301 | 30 | 63 | 99 | 971 |
| 3.65 | 277 | 392 | 29 | 61 | 96 | 941 |
| 3.70 | 269 | 284 | 27.5 | 59 | 93 | 912 |
| 3.75 | 262 | 276 | 26.5 | 58 | 91 | 892 |
| 3.80 | 255 | 269 | 25.5 | 56 | 89 | 873 |
| 3.85 | 248 | 261 | 24 | 55 | 87 | 853 |
| 3.90 | 241 | 253 | 23 | 53 | 84 | 824 |
| 3.95 | 235 | 247 | 22 | 51 | 81 | 794 |
| 4.00 | 229 | 241 | 20.5 | 50 | 79 | 775 |
| 4.05 | 223 | 235 | (20) | 49 | 77 | 755 |
| 4.10 | 217 | 228 | (19) | 48 | 76 | 745 |
| 4.15 | 212 | 223 | (18) | 46 | 73 | 716 |
| 4.20 | 207 | 218 | (17) | 45 | 71 | 696 |
| 4.30 | 197 | 208 | (14) | 43 | 68 | 667 |
| 4.40 | 187 | 197 | (12) | 41 | 65 | 637 |
| 4.50 | 179 | 189 | (10) | 39 | 62 | 608 |
| 4.60 | 170 | 176 | - | 36 | 57 | 559 |
| 4.70 | 163 | 172 | - | 35 | 55 | 539 |
| 4.80 | 156 | 165 | - | 34 | 54 | 530 |
| 4.90 | 149 | 157 | - | 32 | 51 | 500 |
| 5.00 | 143 | 150 | - | 31 | 49 | 481 |
| 5.10 | 137 | 144 | - | 31 | 49 | 481 |
| 5.20 | 131 | 138 | - | 30 | 47 | 461 |
| 5.30 | 126 | 133 | - | 29 | 46 | 451 |
| 5.40 | 121 | 127 | - | 28 | 44 | 431 |
| 5.50 | 116 | 122 | - | 27 | 43 | 422 |
| 5.60 | 111 | 117 | - | 26 | 41 | 402 |
| 5.70 | 107 | 113 | - | 25 | 39 | 382 |
| 5.80 | 103 | 108 | - | 24 | 38 | 373 |
The figures in brackets (over 450) require a tungsten Carbide ball (BS240 - 1986).
HB to HV and HV to HRC conversions are based on A.S.T.M.E. 140.
Rockwell C. scale and tonf/in2 figures in brackets are for guidance only.
| Tensile Strength Ranges | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| P | = | 35 | - | 40 ton/in2 | = | 163 | - | 207 | HB |
| Q | = | 40 | - | 50 | = | 197 | - | 229 | |
| R | = | 45 | - | 55 | = | 207 | - | 248 | |
| S | = | 50 | - | 60 | = | 229 | - | 277 | |
| T | = | 55 | - | 65 | = | 248 | - | 302 | |
| U | = | 60 | - | 70 | = | 277 | - | 321 | |
| V | = | 65 | - | 75 | = | 302 | - | 341 | |
| W | = | 70 | - | 80 | = | 321 | - | 363 | |
| X | = | 75 | - | 85 | = | 341 | - | 388 | |
| Y | = | 80 | - | 90 | = | 363 | - | 401 | |
| Z | = | 100 | + | = | 461 | + | |||
Based on BS970 Pt. 1 (1970)
| Fastener Tensile Ranges | |||||
|---|---|---|---|---|---|
| 3.6 | = | 300-420 N/mm2 | = | 27 ton/in2 max | 116 HB max. |
| 4.6/4.8 | = | 400-520 | = | 26-34 ton in2 | 111-156 HB |
| 5.6/5.8 | = | 500-660 | = | 32-43 | 149-197 |
| 6.6/6.8 | = | 600-740 | = | 39-48 | 179-217 |
| 8.8 | = | 800-980 | = | 51-64 | 235-293 |
| 9.8 | = | 900-1025 | = | 58-66 | 262-302 |
| 10.9 | = | 1000-1150 | = | 65-75 | 293-341 |
| 12.9 | = | 1200 - 1375 | = | 77-88 | 352-401 |
Based on ISO 898-1 (1988)
Over Equivalents
N/mm2=MN/M2=MPa
Kgf=mm2=Kp/mm2