HARDNESS CONVERSION

HARDNESS CONVERSION TABLE FOR CARBON & ALLOY STEELS
All values are approximate

Brinell
Hardness
Number
(Carbide ball)

Rockwell Hardness Numbers

Tensile 
Strength

C
Scale

A
Scale

15N
Scale
Superficial

B
Scale

30T
Scale
Superficial

1000
Lb/Sq In

kgf/mm

66 84.5 92.5

722

64 83.4 91.8

688

62 82.3 91.1

654

60 81.2 90.2

615

58 80.1 89.3

577

56 79.0 88.3 313 220

543

54 78.0 87.4 292 205

512

52 76.8 86.4 273 192

481

50 75.9 85.5 255 179

455

48 74.7 84.5 237 167

443

47 74.1 83.9 229 161

432

46 73.6 83.5 222 156

421

45 73.1 83.0 215 151

409

44 72.5 82.5 208 146

400

43 72.0 82.0 201 141

390

42 71.5 81.5 194 136

381

41 70.9 80.9 188 132

371

40 70.4 80.4 181 127

362

39 69.9 79.9 176 124

353

38 69.4 79.4 171 120

344

37 68.9 78.8 167 117

336

36 68.4 78.3 162 114

327

35 67.9 77.7 157 110

319

34 67.4 77.2 153 108

311

33 66.8 76.6 149 105

301

32 66.3 76.1 145 102

294

31 65.8 75.6 142 100

286

30 65.3 75.0 138 97

279

29 64.7 74.5 135 95

271

28 64.3 73.9 132 93

264

27 63.8 73.3 128 90

258

26 63.3 72.8 125 88

253

25 62.8 72.2 122 86

247

24 62.4 71.6 120 84

243

23 62.0 71.0 117 82

240

100 82.0 116 82

234

99 81.5 112 79

222

97 80.5 106 75

210

95 79.0 101 71

200

93 78.0 96 67

195

92 77.5 93 65

185

90 76.0 89 63

176

88 75.0 85 60

169

86 74.0 81 57

162

84 73.0 78 55

156

82 71.5 75 53

150

80 70.0 72 51

144

78 69.0

139

76 67.5

135

74 66.0

130

72 65.0

125

70 63.5

121

68 62.0

117

66 60.5

114

64 59.5
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