Hardness Conversions Approximate relations between Brinell, Rockwell, Shore, Vickers and Firth hardness and the tensile strengths of S.A.E. carbon and alloy construction steels. C A 15-N 30-N VICKERS KNOOP BRINELL   150 kg Braie 60 kg Braie 16 kg N Braie 30 kg N Braie 10 kg 136* Diamond 500 Gr. & over 3000 kg 10 mm Ball Approx. Tensile Strength ksi Rockwell Rockwell Superficial Rockwell Rockwell Vickers Knoop Brinell** (Standard Ball) 68 67 66 65 64 85.6 85.0 84.5 83.9 83.4 93.2 92.9 92.5 92.2 91.8 84.4 83.6 82.8 81.9 81.1 940 900 865 832 800 920 895 870 846 822 - - - - -   inexact and only for steel 63 62 61 60 59 82.8 82.3 81.8 81.2 80.7 91.4 91.1 90.7 90.2 89.8 80.1 79.3 78.4 77.5 76.5 772 746 720 697 674 799 776 754 732 710 - - - - -   351 58 57 56 55 54 80.1 79.6 79.0 78.5 78.0 89.3   88.90 88.3 87.9 87.4 75.7 74.8 73.9 73.0 72.0 653 633 613 595 577 690 670 650 630 612 615 595 577 560 543 338 325 313 301 292 53 52 51 50 49 77.4 76.8 76.3 75.9 75.2 86.9 86.4 85.9 85.5 85.0 71.2 70.2 69.4 68.5 676.6 560 544 528 513 498 594 576 558 542 526 525 512 496 481 469 283 273 264 255 246 48 47 46 45 44 74.7 74.1 73.6 73.1 72.5 84.5 83.9 83.5 83.0 82.5 66.7 65.8 64.8 64.0 63.1 484 471 458 446 434 510 495 480 466 452 451 442 432 421 409 238 229 221 215 208 42 40 38 36 34 71.5 70.4 69.4 68.4 67.4 81.5 80.4 79.4 78.3 77.2 61.3 59.5 57.7 55.9 54.2 412 392 372 354 336 426 402 380 360 342 390 371 353 336 319 194 182 171 161 152 32 30 28 26 24 22 20 66.3 65.3 64.3 63.3 62.4 61.5 60.5 76.1 75.0 73.9 72.8 71.6 70.5 69.4 52.1 50.4 48.6 46.8 45.0 43.2 41.5 318 302 286 272 260 248 238 326 311 297 284 272 261 251 301 286 271 258 247 237 226 146 138 131 125 119 115 110 B 100 kg 1/16" Ball F 60 kg 1/16" Ball 30-T 30 kg 1/16" Ball A 60 kg & Over Knoop 500 Gr. Br'L 3000 kg Tensile Strength Braie Braie Braie Braie   10 mm Ball   Rockwell Rockwell Rockwell Superficial Rockwell Knoop Brinell Thousand lbs. per sq. in. 100 99 98 97 96 - - - - - 83.1 82.5 81.8 81.1 80.4 61.5 60.9 60.2 59.5 58.9 251 246 241 236 231 240 234 228 222 216 116 114 109 104 102 95 94 93 92 91 - - - - - 70.8 79.1 78.4 77.8 77.1 58.3 57.6 57.0 56.4 55.8 226 221 216 211 206 210 205 200 195 190 100 98 94 92 90 90 89 88 87 86 - - - - - 76.4 75.8 75.1 74.4 73.8 55.2 54.6 54.0 53.4 52.8 201 196 192 188 184 185 180 176 172 169 89 88 86 84 83 85 84 83 82 81 - - - - - 73.1 72.4 71.8 71.1 70.4 52.3 51.7 51.1 50.6 50.0 180 176 173 170 167 165 162 159 156 153 82 81 80 77 73 80 79 78 77 76 - - - - - 69.7 69.1 68.4 67.7 67.1 49.5 48.9 48.4 47.9 47.3 164 161 158 155 152 150 147 144 141 139 72 70 69 68 67 75 74 72 71 68 99.6 99.1 98.0 96.8 95.6 66.4 65.7 64.4 63.1 61.7 46.8 46.3 45.3 44.3 43.3 150 147 143 139 135 137 135 130 125 121 66 65 63 61 59 66 64 62 60 58 94.5 93.4 92.2 91.1 90.0 60.4 59.0 57.7 56.4 55.0 42.3 41.4 40.4 39.5 38.6 131 127 124 120 117 117 114 110 107 104 Even for steel, tensile strength relation to hardness is inexact unless determined for specific material. See ASTM A370 56 54 52 50 48 88.8 87.7 86.5 85.4 84.3 53.7 52.4 51.0 49.7 48.3 37.7 36.8 35.9 35.0 34.1 114 111 109 107 105 101 *87 *85 *83 *81 46 44 42 40 38 83.1 82.0 80.8 79.7 78.6 47.0 45.7 44.3 43.0 41.6 33.3 32.4 31.6 30.7 29.9 103 101 99 97 95 *79 *78 *76 *74 *73 36 34 32 30 77.4 76.3 75.2 74.0 40.3 39.0 37.6 36.3 29.1 28.2 27.4 26.6 93 91 89 87 *71 *70 *68 *67 6