Heico-Lock

Hardness Conversion Chart

Below are approximate equivalent hardness numbers for carbon and alloy steels.

Chart courtesy of the Collaboration for NDT/NDE Education led by the Center for NDE at Iowa State University.

Rockwell Rockwell Superficial Brinell Vickers Knoop Sleroscope Approx. Tensile Strength of Steel (PSI)
A Scale 60kg Diam. Brale B Scale 100kg 1/16″ Ball C Scale 150kg Diam. Brale D Scale 100kg Diam. Brale 15N Scale 15kg Diam. Brale 30N Scale 30kg Diam. Brale 45N Scale 45kg Diam. Brale 3000kg 10mm Ball 500g or Greater Load
  80 87 97 92 87 1865
92 79 86 92 87 1787
91 78 85 96 91 86 1710
91 77 84 91 85 1633
90 76 83 96 90 84 1556
90 75 83 89 83 1478
89 74 82 95 89 82 1400
89 73 81 88 81 1323
88 72 80 95 87 80 1245
87 71 80 87 79 1160
87 70 79 94 86 78 1076 99
86 69 78 85 77 1004 98
85.6 68 76.9 93.2 84.4 75.4 940 920 97
85.3 67.5 76.5 93 84 74.8 920 908 96
85 67 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 73.8 91.8 81.1 71 800 822 88
83 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 79.1 68.6 740 772 84
81.8 61 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 57.8 69 89.2 75.5 64.1 611* 650 687 78
79.8 57.3 68.7 89 75.1 63.5 601* 640 677 77 309,000
79.5 56.8 68.3 88.8 74.6 63 591* 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 88 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 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 65.4 86.9 71.2 58.6 525* 560 594 71
77 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 57 507* 540 572 69
76.4 51.1 63.9 86 69.5 56.2 497* 530 561 68 253,000
76.1 50.5 63.5 85.7 69 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 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 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 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 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 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 29.5 275 290 300 41
64.2 27.8 46 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 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 43.1 71.6 45 24.3 247 260 272 37 122,000
62 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
95 209 220 234 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
85 162 170 185 25 79,000
165
81.7 152 160 175 23
155
78.7 143 150 164 22 71,000
145
75 133 140 154 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 90 95 107
48 86 90 102
41 81 85 97

* Values for tungsten carbide ball only