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

-

-