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 Thousand lbs.
Rockwell Rockwell Rockwell
Superficial
Rockwell Knoop Brinell 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

All relative hardness values on this card are averages of tests on various metals whose different properties prevent establishment of exact mathematical conversions. These values are consistent with ASTM E 140 Tables 1 and 2 and for non-austenitic steels. It is recommended that ASTM standards E 140, E 10, E18, E92, E110, E384 and A 370 ( involving hardness tests on metals) be reviewed prior to interpreting hardness conversion values.

* Below Brinell 101 tests were made with only 500 kg lodad and 10 mm ball.

** Above Brinell 451 HB tests were made with 10 mm carbide ball.