Approximate Hardness Conversion

Brinell hardness number
Rockwell C 150 kg. 120° cone
Rockwell A 60 kg 120° cone
Rockwell B 100 kg 1/16" ball
Vickers hardness number
knop hardness number 500g>
-
70
86.5
-
-
-
-
69
86
-
-
-
-
68
85.5
-
-
-
-
67
85
-
-
-
767
66.5
84.7
-
-
-
745
65.5
84.2
-
840
852
712
64
83.5
-
783
808
682
61.5
82
-
737
768
653
60
81
-
697
732
627
58.5
80.2
-
667
703
601
57.5
79.2
-
640
677
578
56
79
-
615
652
555
54.5
78.2
-
591
626
534
53.5
77.7
-
569
604
514
52
77
-
547
579
495
51
76.5
-
528
558
477
49.5
75.7
-
508
537
461
48.5
74.7
-
491
518
444
47
74.2
-
472
496
429
45.5
73.2
-
455
476
415
44.5
72.7
-
440
459
401
43
72
-
425
441
388
42
71.5
-
410
423
375
40.5
70.7
-
395
407
363
39
70
-
383
392
352
38
69.5
110
372
379
341
36.5
68.7
109
360
367
331
35.5
68.2
108.5
350
356
321
34.5
67.7
108
339
345
311
33
67
107.5
328
336
302
32
66.5
107
319
327
293
31
66
106
309
318
285
30
65.5
105.5
301
310
277
29
65
104.5
292
302
269
27.5
64.2
104
284
294
262
26.5
63.7
103
276
286
255
25.5
63.2
102
269
279
248
24
62.5
101
261
272
241
23
61.8
100
253
265
235
21.5
61
99
247
259
229
20.5
60
98
241
253
223
19
59.5
97
234
247
217
17.5
59.2
96.5
228
242
212
16
58.5
95.5
222
237
207
15
57.7
94.5
218
232
197
12.5
57
93
207
222
187
10
55.7
90.5
196
212
179
8
55
89
188
202
170
5
53.5
87
178
194
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