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Hardness Conversion Chart

Tensile Strength (N/mm2)Hardness VickersHardness Brinell*HRBHRFHRCHRA
77024022898.1114.320.360.7
78524523321.361.2
80025023899.5115.122.261.6
82025524223.162.0
835260247(101)24.062.4
85026525225.862.7
865270257(102)25.863.1
88027526126.463.5
900208266(104)27.163.8
91528527127.864.2
930290276(105)28.564.5
95029528029.264.8
96530028529.865.2
99531029531.065.8
103032030432.266.4
106033031433.367.0
109534032334.467.6
112535033335.568.1
115536034236.668.7
119037035237.769.2
122038036138.869.8
125539037139.870.3
129040038040.870.8
132041039041.871.4
135042039942.771.8
138543040943.672.3
142044041844.572.8
145545042845.373.3
148546043746.173.6
152047044746.974.1
1555480(456)47.774.5
1595490(466)48.474.8
1630500(475)49.175.3
1665510(485)49.875.7
1700520(494)50.576.1
1740530(504)51.176.4
1775540(513)51.776.7
1810550(523)52.377.0
1845560(532)53.077.4
1880570(542)53.677.8
1920580(551)54.178.0
1955590(561)54.778.4
1995600(570)55.278.6
2030610(580)55.778.9
2070620(589)56.379.2
2105630(599)56.579.5
2145640(608)57.379.8
2180650(618)58.780.0
66058.380.3
67058.880.6
68059.280.8
69059.781.1
70060.181.3
72061.081.8
74061.882.2
76062.582.6
78063.383.0
80064.083.4
82064.783.8
84065.384.1
86065.984.4
88066.484.7
90067.085.0
92067.585.3
94068.885.6
* calculate from HB = 0.95 x HV
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Ball Hardness Corrections for Curvatures

Ball DiaRockwell 'C' Readings
(mm)5556575859606162636465
3.1756.15.75.45.14.84.54.24.03.83.63.4
3.9685.65.35.04.74.44.13.83.63.43.23.0
4.7625.14.74.34.03.83.63.43.23.02.82.5
5.5624.64.34.03.73.53.33.12.92.72.52.3
6.3504.13.83.63.33.12.92.72.52.32.11.8
7.0003.73.43.23.02.82.62.42.22.01.81.6
7.9383.12.92.72.62.42.22.01.91.71.51.3
8.0003.12.92.72.62.42.22.01.91.71.51.3
9.0002.72.52.42.22.01.91.71.51.41.21.1
9.5252.52.32.22.01.91.81.61.41.21.11.0
10.0002.42.22.01.91.81.71.51.31.11.00.9
11.0002.12.01.81.71.61.51.31.10.90.80.7
12.0001.91.71.61.51.41.31.11.00.80.70.6
12.7001.81.71.61.51.41.21.00.90.70.60.5
13.0001.81.71.61.51.41.21.00.90.70.60.5
14.0001.61.51.41.31.21.00.90.80.60.50.4
15.0001.51.41.31.21.10.90.80.70.50.40.3
15.8751.41.31.21.11.00.90.80.70.50.40.3
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This table is useful for converting Rockwell 'C' readings taken on ball surfaces to equivalent value applicable to flat surfaces. Hardness readings of balls are affected by the curvature and hardness level of the ball. Because of these factors, corrections are necessarily added to the as-read hardness. For ball sizes and hardness values other than shown, values shall be interpolated.

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