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Hardness Conversion Chart

Approximate equivalent hardness numbers for carbon and alloy steels

Rockwell
Rockwell Superficial
Brinell
Vickers
Knoop
Scleroscope
Approx.
Tensile
Strength
of
Steel
(PSI)
A Scale
B Scale
C Scale
D Scale
15N
Scale
30N
Scale
45N
Scale
3000 kg
10 mm
Ball
500 g or
greater
Load

60 kg
Diam.
Brale

100 kg
1/16"
Ball
150 kg Diam.
Brale

100 kg Diam.
Brale

15 kg
Diam.
Brale
30 kg
Diam.
Brale
45 kg
Diam.
Brale
92 - 80.0 87 97 92 87 - 1865 - - -
92 - 79.0 86 - 92 87 - 1787 - - -
91 - 78.0 85 96 91 86 - 1710 - - -
91 - 77.0 84 - 91 85 - 1633 - - -
90 - 76.0 83 96 90 84 - 1556 - - -
90 - 75.0 83 - 89 83 - 1478 - - -
89 - 74.0 82 95 89 82 - 1400 - - -
89 - 73.0 81 - 88 81 - 1323 - - -
88 - 72.0 80 95 87 80 - 1245 - - -
87 - 71.0 80 - 87 79 - 1160 - - -
87 - 70.0 79 94 86 78 - 1076 - 99 -
86 - 69.0 78 - 85 77 - 1004 - 98 -
85.6 - 68.0 76.9 93.2 84.4 75.4 - 940 920 97 -
85.3 - 67.5 76.5 93.0 84.0 74.8 - 920 908 96 -
85.0 - 67.0 76.1 92.9 83.6 74.2 - 900 895 95 -
84.7 - 66.4 75.7 92.7 83.1 73.6 - 880 882 93 -
84.4 - 65.9 75.3 92.5 82.7 73.1 - 860 867 92 -
84.1 - 65.3 74.8 92.3 82.2 72.2 - 840 852 91 -
83.8 - 64.7 74.3 92.1 81.7 71.8 745* 820 837 90 -
83.4 - 64.0 73.8 91.8 81.1 71.0 - 800 822 88 -
83.0 - 63.3 73.3 91.5 80.4 70.2 - 780 806 87 -
82.6 - 62.5 72.6 91.2 79.7 69.4 710* 760 788 86 -
82.2 - 61.8 72.1 91.0 79.1 68.6 - 740 772 84 -
81.8 - 61.0 71.5 90.7 78.4 67.7 - 720 754 83 -
81.3 - 60.1 70.8 90.3 77.6 66.7 653* 700 735 81 -
81.1 - 59.7 70.5 90.1 77.2 66.2 - 690 725 - -
80.8 - 59.2 70.1 89.8 76.8 65.7 - 680 716 80 329,000
80.6 - 58.8 69.8 89.7 76.4 65.3 - 670 706 - 324,000
80.3 - 58.3 69.4 89.5 75.9 64.7 620* 660 697 79 -
80.0 - 57.8 69.0 89.2 75.5 64.1 611* 650 687 78 -
79.8 - 57.3 68.7 89.0 75.1 63.5 601* 640 677 77 309,000
79.5 - 56.8 68.3 88.8 74.6 63.0 591* 630 667 76 -
79.2 - 56.3 67.9 88.5 74.2 62.4 582* 620 657 75 297,000
78.9 - 55.7 67.5 88.2 73.6 61.7 573* 610 646 - -
78.6 - 55.2 67.0 88.0 73.2 61.2 564* 600 636 74 -
78.4 - 54.7 66.7 87.8 72.7 60.5 554* 590 625 73 285,000
78.0 - 54.1 66.2 87.5 72.1 59.9 545* 580 615 72 -
77.8 - 53.6 65.8 87.2 71.7 59.3 535* 570 604 - 274,000
77.4 - 53.0 65.4 86.9 71.2 58.6 525* 560 594 71 -
77.0 - 52.3 64.8 86.6 70.5 57.8 517* 550 583 70 263,000
76.7 - 51.7 64.4 86.3 70.0 57.0 507* 540 572 69 -
76.4 - 51.1 63.9 86.0 69.5 56.2 497* 530 561 68 253,000
76.1 - 50.5 63.5 85.7 69.0 55.6 488* 520 550 67 -
75.7 - 49.8 62.9 85.4 68.3 54.7 479* 510 539 - 243,000
75.3 - 49.1 62.2 85.0 67.7 53.9 471* 500 528 66 -
74.9 - 48.4 61.6 84.7 67.1 53.1 460* 490 517 65 235,000
74.5 - 47.7 61.3 84.3 66.4 52.2 452* 480 505 64 -
74.1 - 46.9 60.7 83.9 65.7 51.3 441 470 494 - 225,000
73.6 - 46.1 60.1 83.6 64.9 50.4 433 460 482 62 -
73.3 - 45.3 59.4 83.2 64.3 49.4 425 450 471 - -
72.8 - 44.5 58.8 82.8 63.5 48.4 415 440 459 59 210,000
72.3 - 43.6 58.2 82.3 62.7 47.4 405 430 447 58 -
71.8 - 42.7 57.5 81.8 61.9 46.4 397 420 435 57 -
71.4 - 41.8 56.8 81.4 61.1 45.3 388 410 423 56 195,000
70.8 - 40.8 56.0 80.8 60.2 44.1 379 400 412 55 -
70.3 - 39.8 55.2 80.3 59.3 42.9 369 390 400 - -
69.8 - 38.8 54.4 79.8 58.4 41.7 360 380 389 52 -
69.2 - 37.7 53.6 79.2 57.4 40.4 350 370 378 51 176,000
68.7 - 36.6 52.8 78.6 56.4 39.1 341 360 367 50 -
68.1 - 35.5 51.9 78.0 55.4 37.8 331 350 356 48 166,000
67.6 - 34.4 51.1 77.4 54.4 36.5 322 340 346 47 -
67.0 - 33.3 50.2 76.8 53.6 35.2 313 330 337 46 -
66.4 - 32.2 49.4 76.2 52.3 33.9 303 320 328 45 150,000
65.8 - 31.0 48.4 75.6 51.3 32.5 294 310 318 - -
65.2 - 29.8 47.5 74.9 50.2 31.1 284 300 309 42 141,000
64.8 - 29.2 47.1 74.6 49.7 30.4 280 295 305 - -
64.5 - 28.5 46.5 74.2 49.0 29.5 275 290 300 41 -
64.2 - 27.8 46.0 73.8 48.4 28.7 270 285 296 - 133,000
63.8 - 27.1 45.3 73.4 47.8 27.9 265 280 291 40 -
63.5 - 26.4 44.9 73.0 47.2 27.1 261 275 286 39 129,000
63.1 - 25.6 44.3 72.6 46.4 26.2 256 270 282 38 -
62.7 - 24.8 43.7 72.1 45.7 25.2 252 265 277 - -
62.4 - 24.0 43.1 71.6 45.0 24.3 247 260 272 37 122,000
62.0 - 23.1 42.2 71.1 44.2 23.2 243 255 267 - -
61.6 99.5 22.2 41.7 70.6 43.4 22.2 238 250 262 36 -
61.2 - 21.3 41.1 70.1 42.5 21.1 233 245 258 35 115,000
60.7 98.1 20.3 40.3 69.6 41.7 19.9 228 240 253 34 -
- - - - - - - - 235 - - -
- 96.7 - - - - - 219 230 243 33 105,000
- - - - - - - - 225 - - -
- 95.0 - - - - - 209 220 234 32 100,000
- - - - - - - - 215 - - -
- 93.4 - - - - - 200 210 226 30 98,000
- - - - - - - - 205 - - -
- 91.5 - - - - - 190 200 216 29 -
- - - - - - - - 195 - - 90,000
- 89.5 - - - - - 181 190 206 28 -
- - - - - - - - 185 - - -
- 87.1 - - - - - 171 180 196 26 83,000
- - - - - - - - 175 - - -
- 85.0 - - - - - 162 170 185 25 79,000
- - - - - - - - 165 - - -
- 81.7 - - - - - 152 160 175 23 -
- - - - - - - - 155 - - -
- 78.7 - - - - - 143 150 164 22 71,000
- - - - - - - - 145 - - -
- 75.0 - - - - - 133 140 154 21 -
- - - - - - - - 135 - - -
- 71.2 - - - - - 124 130 143 20 63,000
- - - - - - - - 125 - - -
- 66.7 - - - - - 114 120 133 18 -
- - - - - - - - 115 - - 56,000
- 62.3 - - - - - 105 110 123 - -
- - - - - - - - 105 - - -
- 56.2 - - - - - 95 100 112 - -
- 52.0 - - - - - 90 95 107 - -
- 48.0 - - - - - 86 90 102 - -
- 41.0 - - - - - 81 85 97 - -

* Values for tungsten carbide ball only

To download a printable pdf, click here.

References:
Hardness Testing, ASM Internationals, Metals Park, OH, 1987
www.engineersedge.com
www.corrosionsource.com

 

  
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Partial support for this work was provided by the NSF-ATE (Advanced Technological Education) program through grant #DUE 0101709. Opinions expressed are those of the authors and not necessarily those of the National Science Foundation.