Conversions All values, except WMN, are consistent with ASTM E140 Tables 1 and 2, and ASTM A370 Tables 3A and 3B, where applicable. WMN or Wilson Microfi cial Numbers were developed by Wilson Instruments in the Wilson Standards laboratory and are not derived from ASTM.
Cylindrical Corrections Values are consistent with ASTM E18 Table 6,7,13, and 14Hardness vs. Minimum Thickness Values are consistent with ASTM E18 Tables 4, 5, 11, and 12 except for D and G scale values, which are obtained from indentation hardness testing by Vincent E. Lysaght.
Rockwell Superfi cial Knoop Brinell TensileStrength
Micro-fi cial
B F G A E H K 15-T 30-T 45-T HK HB HBHV KSI WMN
100 kg
1/16”ball
60 kg
1/16” ball
150 kg
1/16”ball
60 kg
Brale
100 kg
1/8”ball
60 kg
1/8” ball
150 kg
1/8”ball
15kg
1/16”ball
30 kg
1/16” ball
45kg
1/16”ball
500 gmandover
500 kg10 mm ball
3000 kg
10 kg
1000lbs/sq in
1000 gm
1009998
82.581.079.0
61.560.960.2
93.192.892.5
83.182.581.8
72.971.970.9
251246241
201195189
240234228
116114109
730725719
979695
77.576.074.0
59.558.958.3
92.191.891.5
81.180.479.8
69.968.967.9
236231226
184179175
222216210
104102100
713707701
949392
72.571.069.0
57.657.056.4
NA100
91.290.890.5
79.178.477.8
66.965.964.8
221216211
171167163
205200195
989492
696690684
919089
67.566.064.0
55.855.254.6
99.598.598.0
90.289.989.5
77.176.475.8
63.862.861.8
206201196
160157154
190185180
908988
679674668
888786
62.561.059.0
54.053.452.8
97.096.595.5
89.288.988.6
75.174.473.8
60.859.858.8
192188184
151148145
176172169
868483
662656651
858483
57.556.054.0
52.351.751.1
94.594.093.0
88.287.987.6
73.172.471.8
57.856.855.8
180176173
142140137
165162159
828180
646640634
828180
52.551.049.0
50.650.049.5
92.091.090.5
87.386.986.6
71.170.469.7
54.853.852.8
170167164
135133130
156153150
777372
629624618
797877
47.546.044.0
48.948.447.9
89.588.588.0
86.386.085.6
69.168.467.7
51.850.849.8
161158155
128126124
147144141
706968
612607602
767574
NA99.699.1
42.541.039.0
47.346.846.3
87.086.085.0
85.385.084.7
67.166.465.7
48.847.846.8
152150147
122120118
139137135
676665
596592587
737271
98.598.097.4
37.536.034.5
45.845.344.8
NA100
84.583.582.5
84.384.083.7
65.164.463.7
45.844.843.8
145143141
116114112
132130127
646362
581576571
706968
96.896.295.6
32.531.029.5
44.343.843.3
99.599.098.0
81.581.080.0
83.483.082.7
63.162.461.7
42.841.840.8
139137135
110109107
125123121
616059
566561556
676665
95.194.593.9
28.026.525.0
42.842.341.8
97.597.096.0
79.078.077.5
82.482.181.8
61.060.459.7
39.838.737.7
133131129
106104102
119117116
585756
551546542
646362
93.492.892.2
23.522.020.5
41.440.940.4
95.595.094.5
76.575.574.5
81.481.180.8
59.058.457.7
36.735.734.7
127125124
1019998
114112110
NA 537532527
616059
91.791.190.5
19.017.516.0
40.039.539.0
93.593.092.5
74.073.072.0
80.580.179.8
57.056.455.7
33.732.731.7
122120118
969594
108107106
522517512
585756
90.089.488.8
14.513.011.5
38.638.137.7
92.091.090.5
71.070.569.5
79.579.278.8
55.054.453.7
30.729.728.7
117115114
929190
104103101
507502497
555453
88.287.787.1
10.08.57.0
37.236.836.3
90.089.589.0
68.568.067.0
78.578.277.9
53.052.451.7
27.726.725.7
112111110
898786
100NA
492487482
525150
86.586.085.4
5.54.02.5
35.935.535.0
88.087.587.0
66.065.064.5
77.577.276.9
51.050.349.7
24.723.722.7
109108107
858483
477472468
494847
84.884.383.7
NA 34.634.133.7
86.585.585.0
63.562.561.5
76.676.275.9
49.048.347.7
21.720.719.7
106105104
828180
463458453
464544
83.182.682.0
33.332.932.4
84.584.083.5
61.060.059.0
75.675.374.9
47.046.345.7
18.717.716.7
103102101
807978
448444439
434241
81.480.880.3
32.031.631.2
82.582.081.5
58.057.556.5
74.674.374.0
45.044.343.7
15.714.713.6
1009998
777675
435430426
403938
79.779.178.6
30.730.329.9
81.080.079.5
55.554.554.0
73.673.373.0
43.042.341.6
12.611.610.6
979695
757473
422417413
373635
78.077.476.9
29.529.128.7
79.078.578.0
NA10099.5
53.052.051.5
72.772.372.0
41.040.339.6
9.68.67.6
949392
727271
409404401
343332
76.375.775.2
28.227.827.4
77.076.576.0
99.098.898.5
50.549.548.5
71.771.471.0
39.038.337.6
6.65.64.6
919089
706969
396392388
313029
74.674.073.5
27.026.626.0
75.575.074.0
98.097.897.5
48.047.046.0
70.770.470.0
37.036.335.6
3.62.61.0
888787
686766
384380376
282726
73.072.572.0
25.525.024.5
73.573.072.5
97.096.596.3
45.044.543.5
69.369.569.0
34.534.033.0
NA 868584
666565
372369365
252423
71.070.570.0
24.324.023.5
72.071.070.5
96.095.595.3
42.541.541.0
68.868.568.0
32.532.031.0
838282
646463
361357353
222120
69.569.068.5
23.022.522.0
70.069.568.5
95.094.594.3
40.039.038.0
67.867.567.3
30.529.529.0
818180
626261
350346343
191817
68.067.066.5
21.521.321.0
68.067.567.0
94.093.593.0
37.536.535.5
67.066.566.3
28.527.527.0
797878
616060
339335332
161514
66.065.565.0
20.520.0NA
66.565.565.0
92.892.592.0
35.034.033.0
66.065.565.3
26.025.525.0
777675
595959
329325322
131211
64.564.063.5
64.564.063.5
91.891.591.0
32.031.530.5
65.064.564.3
24.023.523.0
757473
585857
318314311
1098
63.062.061.5
62.562.061.5
90.590.390.0
29.529.028.0
64.063.863.5
22.021.520.5
727171
575756
308304300
765
61.060.560.0
61.060.560.0
89.589.389.0
27.026.025.5
63.062.862.5
20.019.518.5
706969
565555
297293289
432
59.559.058.0
59.058.558.0
88.588.087.8
24.523.523.0
62.061.861.5
18.017.016.5
696868
555454
286283279
10
57.557.0
57.557.0
87.587.0
22.021.0
61.060.5
16.015.0
6363
5453
276272
Soft Steel, Grey and Malleable Cast Iron and Most Non-Ferrous Metals Scales C, D, A
Brale Diamond IndenterDiameter of Specimen - inches (mm)
ObservedReading
1/8(3.2)
1/4(6.4)
3/8(10)
1/2(13)
5/8(16)
3/4(19)
7/8(22)
1(25)
1-1/4(32)
1-1/2(38)
908580
NA 0.50.50.5
00.50.5
00.50.5
00
0.5
00
0.5
000
000
000
000
757065
1.01.01.5
0.51.01.0
0.50.51.0
0.50.50.5
0.50.50.5
0.50.50.5
00.50.5
000
000
605550
1.52.02.5
1.01.52.0
1.01.01.5
0.51.01.0
0.50.51.0
0.50.50.5
0.50.50.5
00.50.5
00
0.5454035
3.03.54.0
2.02.53.0
1.52.02.0
1.01.51.5
1.01.01.5
1.01.01.0
0.51.01.0
0.50.50.5
0.50.50.5
302520
5.05.56.0
3.54.04.5
2.53.03.5
2.02.52.5
1.52.02.0
1.51.51.5
1.01.01.5
1.01.01.0
0.51.01.0
Scales B, F, G1/16-in Ball Indenter
Diameter of Specimen - inches (mm)
ObservedReading
1/8(3.2)
1/4(6.4)
3/8(10)
1/2(13)
5/8(16)
3/4(19)
7/8(22)
1(25)
1-1/4(32)
1-1/2(38)
1009080
NA 3.54.05.0
2.53.03.5
1.52.02.5
1.51.52.0
1.01.51.5
1.01.51.5
0.51.01.5
NA NA
706050
6.07.08.0
4.05.05.5
3.03.54.0
2.53.03.5
2.02.53.0
2.02.02.5
1.52.02.0
403020
9.010.011.0
6.06.57.5
4.55.05.5
4.04.54.5
3.03.54.0
2.53.03.5
2.52.53.0
100
12.012.5
8.08.5
6.06.5
5.05.5
4.04.5
3.53.5
3.03.0
Scales 15-N, 30-N, 45-NN Brale Diamond Indenter
Diameter of Specimen - inches (mm)
ObservedReading
1/8(3.2)
1/4(6.4)
3/8(10)
1/2(13)
5/8(16)
3/4(19)
7/8(22)
1(25)
1-1/4(32)
1-1/2(38)
908580
00.51.0
00.50.5
00.50.5
00.50.5
00
0.5
000
000
000
NA NA
757065
1.52.02.5
1.01.01.5
0.51.01.0
0.50.50.5
0.50.50.5
0.50.50.5
00.50.5
00.50.5
605550
3.03.53.5
1.52.02.0
1.01.51.5
1.01.01.0
1.01.01.0
0.50.51.0
0.50.51.0
0.50.50.5
454035
4.04.55.0
2.02.52.5
1.51.52.0
1.01.51.5
1.01.01.0
1.01.01.0
1.01.01.0
1.01.01.0
302520
5.55.56.0
3.03.03.0
2.02.02.0
1.51.51.5
1.51.51.5
1.01.51.5
1.01.51.5
1.01.01.5
Scales 15-T, 30-T, 45-T1/16-in Ball Indenter
Diameter of Specimen - inches (mm)
ObservedReading
1/8(3.2)
1/4(6.4)
3/8(10)
1/2(13)
5/8(16)
3/4(19)
7/8(22)
1(25)
1-1/4(32)
1-1/2(38)
908070
1.53.05.0
1.02.03.5
1.01.52.5
0.51.52.0
0.51.01.5
0.51.01.0
0.51.01.0
0.50.51.0
NA NA
605040
6.58.5
10.0
4.55.56.5
3.04.04.5
2.53.03.5
2.02.53.0
1.52.02.5
1.52.02.0
1.51.52.0
3020
11.513.0
7.59.0
5.06.0
3.54.5
3.54.5
2.53.0
2.02.0
2.02.0
Cylindrical Correction Chart 53Cylindrical work corrections to be added to observed
Rockwell number for scales indicated
Rockwell Superfi cial Vickers Knoop Brinell TensileStrength
Micro-fi cial
C A D G 15-N 30-N 45-N HV HK HB KSI WMN
150 kg
Brale
60 kg
Brale
100 kg
Brale
150 kg
1/16” ball
15 kg N
Brale
30 kg N
Brale
45 kg N
Brale
10 kg
500 gmand over
3000 kg10 mm ball
1000 lbs/sq in
1000 gm
807978
92.091.591.0
86.585.584.5
96.596.396.0
92.091.591.0
87.086.585.5
186517871710
---
---
777675
90.590.089.5
84.083.082.5
95.895.595.3
90.590.089.0
84.583.582.5
163315561478
---
---
747372
89.088.588.0
81.581.080.0
95.094.894.5
88.588.087.0
81.580.579.5
140013231245
---
---
717069
87.086.586.0
79.578.578.0
94.394.093.5
86.586.085.0
78.577.576.5
116010761004
-972946
-953949
686766
85.685.084.5
76.976.175.4
93.292.992.5
84.483.682.8
75.474.273.3
940900865
920895870 NA
945942938
656463
83.983.482.8
74.573.873.0
92.291.891.4
81.981.180.1
72.071.069.9
832800772
846822799
739722706
934930926
626160
82.381.881.2
72.271.570.7
91.190.790.2
79.378.477.5
68.867.766.6
746720697
776754732
688670654 NA
922917913
595857
80.780.179.6
69.969.268.5
89.889.388.9
76.675.774.8
65.564.363.2
674653633
710690670
634615595
351338325
909904900
565554
79.078.578.0
67.766.966.1
88.387.987.4
73.973.072.0
62.060.959.8
613595577
650630612
577560543
313301292
896891887
535251
77.476.876.3
65.464.663.8
86.986.485.9
71.270.269.4
58.657.456.1
560544528
594576558
525512496
283273264
883879874
504948
75.975.274.7
63.162.161.4
85.585.084.5
68.567.666.7
55.053.852.5
513498484
542526510
481469455
255246238
870865861
474645
74.173.673.1
60.860.059.2
83.983.583.0
65.864.864.0
51.450.349.0
471458446
495480466
443432421
229221215
856851847
444342
72.572.071.5
58.557.756.9
82.582.081.5
63.162.261.3
47.846.745.5
434423412
452438426
409400390
208201194
842837832
414039
70.970.469.9
56.255.454.6
80.980.479.9
60.459.558.6
44.343.141.9
402392382
414402391
381371362
188182177
827822817
383736
69.468.968.4
53.853.152.3
79.478.878.3
57.756.855.9
40.839.638.4
372363354
380370360
353344336
171166161
812807802
353433
67.967.466.8
51.550.850.0
77.777.276.6
55.054.253.3
37.236.134.9
345336327
351342334
327319311
156152149
798793788
323130
66.365.865.3
49.248.447.7
NA92.0
76.175.675.0
52.151.350.4
33.732.531.3
318310302
326318311
301294286
146141138
783778773
292827
64.664.363.8
47.046.145.2
91.090.089.0
74.573.973.3
49.548.647.7
30.128.927.8
294286279
304297290
279271264
135131128
768762757
262524
63.362.862.4
44.643.843.1
88.087.086.0
72.872.271.6
46.845.945.0
26.725.524.3
272266260
284278272
258253247
125123119
751746741
232221
62.061.561.0
42.141.640.9
84.583.582.5
71.070.569.9
44.043.242.3
23.122.020.7
254248243
266261256
243237231
117115112
736730725
20 60.5 40.1 81.0 69.4 41.5 19.6 238 251 226 110 720
Hardened Steel and Hardened Alloys
Note 1: A 10 mm steel ball was used for 450 BHN and below. A 10 mm carbide ball was used above 450 BHN.2: The tensile strength relation to hardness is not exact, even for steel, unless it is determined for a specifi c material.
These corrections are approximate only and represent the averages to the nearest 1/2 Rockwell number.
Any greater thickness and
hardness can besafely tested onindicated scale
RockwellSuperfi cial
Hardness Scales
RockwellRegular
Hardness Scales
15N 30N 45N A D C15kgf
30kgf
45kgf
60kgf
100kgf
150kgf
Thicknessinches (mm)
N BraleIndenter
BraleIndenter
.006 (0.15) 92 - - - - -
.008 (0.20) 90 - - - - -
.010 (0.25) 88 - - - - -
.012 (0.30) 83 82 77 - - -
.014 (0.36) 76 78.5 74 - - -
.016 (0.41) 68 74 72 86 - -
.018 (0.46) × 66 68 84 - -
.020 (0.51) × 57 63 82 77 -
.022 (0.56) × 47 58 79 75 69
.024 (0.61) × × 51 76 72 67
.026 (0.66) × × 37 71 68 65
.028 (0.71) × × 20 67 63 62
.030 (0.76) × × × 60 58 57
.032 (0.81) × × × × 51 52
.034 (0.86) × × × × 43 45
.036 (0.91) × × × × × 37
.038 (0.96) × × × × × 28
.040 (1.02) × × × × × 20Any greater
thickness andhardness can besafely tested onindicated scale
RockwellSuperfi cial
Hardness Scales
RockwellRegular
Hardness Scales
15-T 30-T 45-T F B G15kgf
30kgf
45kgf
60kgf
100kgf
150kgf
Thicknessinches (mm)
1/16-in BallIndenter
1/16-in BallIndenter
.010 (0.25) 91 - - - - -
.012 (0.30) 86 - - - - -
.014 (0.36) 81 80 - - - -
.016 (0.41) 75 72 71 - - -
.018 (0.46) 68 64 62 - - -
.020 (0.51) × 55 53 - - -
.022 (0.56) × 45 43 - - -
.024 (0.61) × 34 31 98 94 94
.026 (0.66) × × 18 91 87 87
.028 (0.71) × × 4 85 80 76
.030 (0.76) × × × 77 71 68
.032 (0.81) × × × 69 62 59
.034 (0.86) × × × × 52 50
.036 (0.91) × × × × 40 42
.038 (0.96) × × × × 28 31
.040 (1.02) × × × × × 22
Hardness vs Minimum Thickness Chart 55
X = No minimum hardness. These are approximate numbers only.
The values shown are approximate only. This chart is intended primarily as a reference guide.
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Conversion Chart
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