Brinell Hardness Number - BHN
The Brinell hardness test is commonly used to determine the hardness of materials like metals and alloys.
The test is achieved by applying a known load to the surface of the tested material through a hardened steel ball of known diameter. The diameter of the resulting permanent impression in the tested metal is measured and the Brinell Hardness Number calculated as
BHN = 2 P / (π D (D - (D2 - d2)1/2)) (1)
where
BHN = Brinell Hardness Number
P = load on the indenting tool (kg)
D = diameter of steel ball (mm)
d = measure diameter at the rim of the impression (mm)
It is desirable that the test load are limited to a impression diameter in the range of 2.5 to 4.75 mm.
Approximate loads and Brinell Hardness Numbers:
| Brinell Hardness Number | Load (kg) |
|---|---|
| 160 - 600 | 3000 |
| 80 - 300 | 1500 |
| 26 - 100 | 500 |
Typical Brinell Hardness Numbers for Metals
| Material | Brinell Hardness Number |
|---|---|
| Soft brass | 60 |
| Mild steel | 130 |
| Annealed chissel steel | 235 |
| White cast iron | 415 |
| Nitrided surface | 750 |
Steel Hardness versus Strength
| Brinell | Vickers | Rockwell | Equivalent Rm | ||||
|---|---|---|---|---|---|---|---|
|
|
Hardness HB |
Hardness HV |
Hardness B |
Hardness C |
(tonf/in2) |
(kgf/mm2) |
(N/mm2) |
| 2.50 | 601 | 640 | - | 57.0 | - | - | - |
| 2.55 | 578 | 615 | - | 56.0 | - | - | - |
| 2.60 | 555 | 591 | 120 | 54.5 | - | - | - |
| 2.65 | 534 | 569 | 119 | 53.5 | - | - | - |
| 2.70 | 514 | 547 | 119 | 52.0 | - | - | - |
| 2.75 | 495 | 528 | 117 | 51.0 | - | - | - |
| 2.80 | 477 | 508 | 117 | 49.5 | - | - | - |
| 2.85 | 461 | 491 | 116 | 48.5 | 101 | 160 | 1569 |
| 2.90 | 444 | 474 | 115 | 47.0 | 98 | 155 | 1520 |
| 2.95 | 429 | 455 | 115 | 45.5 | 95 | 150 | 1471 |
| 3.00 | 415 | 440 | 114 | 44.5 | 92 | 145 | 1422 |
| 3.05 | 401 | 425 | 113 | 43.0 | 88 | 139 | 1363 |
| 3.10 | 388 | 410 | 112 | 42.0 | 85 | 134 | 1314 |
| 3.15 | 375 | 396 | 112 | 40.5 | 82 | 129 | 1265 |
| 3.20 | 363 | 383 | 110 | 39.0 | 80 | 126 | 1236 |
| 3.25 | 352 | 372 | 110 | 38.0 | 77 | 121 | 1187 |
| 3.30 | 341 | 360 | 109 | 36.5 | 75 | 118 | 1157 |
| 3.35 | 331 | 350 | 109 | 35.5 | 73 | 114 | 1118 |
| 3.40 | 321 | 339 | 108 | 34.5 | 71 | 111 | 1089 |
| 3.45 | 311 | 328 | 108 | 33.0 | 68 | 107 | 1049 |
| 3.50 | 302 | 319 | 107 | 32.0 | 66 | 104 | 1020 |
| 3.55 | 293 | 309 | 106 | 31.0 | 64 | 101 | 990 |
| 3.60 | 285 | 301 | 105 | 30.0 | 63 | 99 | 971 |
| 3.65 | 277 | 292 | 104 | 29.0 | 61 | 96 | 941 |
| 3.70 | 269 | 284 | 104 | 27.5 | 59 | 93 | 912 |
| 3.75 | 262 | 276 | 103 | 26.5 | 58 | 91 | 892 |
| 3.80 | 255 | 269 | 102 | 25.5 | 56 | 89 | 873 |
| 3.85 | 248 | 261 | 102 | 24.0 | 55 | 87 | 853 |
| 3.90 | 241 | 253 | 100 | 23.0 | 53 | 84 | 824 |
| 3.95 | 235 | 247 | 99 | 22.0 | 51 | 81 | 794 |
| 4.00 | 229 | 241 | 98 | 20.5 | 50 | 79 | 775 |
| 4.05 | 223 | 235 | 97 | - | 49 | 77 | 755 |
| 4.10 | 217 | 228 | 96 | - | 48 | 76 | 745 |
| 4.15 | 212 | 223 | 96 | - | 46 | 73 | 716 |
| 4.20 | 207 | 218 | 95 | - | 45 | 71 | 696 |
| 4.30 | 197 | 208 | 93 | - | 43 | 68 | 667 |
| 4.40 | 187 | 197 | 91 | - | 41 | 65 | 637 |
| 4.50 | 179 | 189 | 89 | - | 39 | 62 | 608 |
| 4.60 | 170 | 179 | 87 | - | 36 | 57 | 559 |
| 4.70 | 163 | 172 | 85 | - | 35 | 55 | 539 |
| 4.80 | 156 | 165 | 83 | - | 34 | 54 | 530 |
| 4.90 | 149 | 157 | 81 | - | 32 | 51 | 500 |
| 5.00 | 143 | 150 | 79 | - | 31 | 49 | 481 |
| 5.10 | 137 | 144 | 77 | - | 31 | 49 | 481 |
| 5.20 | 131 | 138 | 74 | - | 30 | 47 | 461 |
| 5.30 | 126 | 133 | 72 | - | 29 | 46 | 451 |
| 5.40 | 121 | 127 | 70 | - | 28 | 44 | 431 |
| 5.50 | 116 | 122 | 68 | - | 27 | 43 | 422 |
| 5.60 | 111 | 117 | 66 | - | 26 | 41 | 402 |
| 5.70 | 107 | 113 | 64 | - | 25 | 39 | 382 |
| 5.80 | 103 | 108 | 61 | - | 24 | 38 | 373 |
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