Hardness Conversion Chart

Hardness is a surface property where indentation, scratching or wear is resisted.

The higher the hardness the more resistant the surface and the more difficult surface operations such as cutting and machining are.
Testing the hardness of steels can be used an indication of how they can be manipulated (formed, machined etc.) and how they will perform mechanically.

Hardness test methods

Common tests for hardness in metals involve measuring the resistance to indentation by a hardened steel or diamond ball, cone or pyramid.

The common test methods include:

Brinell Hardness (HB)Vickers Hardness (HV)Rockwell (HRB)Rockwell (HRC)UTS (N/mm2)

-

640

-

57

-

-

615

-

56

-

-

591

-

54.5

-

-

569

-

53.5

-

-

547

-

52

-

-

528

-

51

-

-

508

-

49.5

-

-

491

-

48.5

1539

444

474

-

47

1520

429

455

-

45.5

1471

415

440

-

44.5

1422

401

425

-

43

1363

388

410

-

42

1314

375

396

-

40.5

1265

363

383

-

39

1236

352

372

-

38

1187

341

360

-

36.5

1157

331

350

-

35.5

1118

321

339

-

34.5

1089

311

328

-

33

1049

302

319

-

32

1020

293

309

-

31

990

285

301

-

30

971

277

292

-

29

941

269

284

-

27.5

912

262

276

-

26.5

892

255

269

100

25.5

873

248

261

99

24

853

241

253

98

23

824

235

247

97

22

794

229

241

96

20.5

775

223

235

-

-

755

217

228

95

-

745

212

223

94

-

716

207

218

93

-

696

197

208

91

-

667

187

197

89

-

637

179

189

87

-

608

170

179

85

-

559

163

172

83

-

539

156

165

81

-

530

149

157

79

-

500

143

150

77

-

481

137

144

74

-

471

131

138

72

-

461

126

133

69

-

451

121

127

67

-

431

116

122

64

-

422

111

117

61

-

402

107

113

-

-

382

103

108

-

-

373

Hardness conversions between different scales

There are several hardness scale conversion systems, including BS 860 and ASTM E140.

The table shows a set of values that has been used for stainless steels and also includes a tensile strength (UTS) comparison. The Rockwell B values are superimposed on this table using an approximation from ASTM E140 Table5, which compares Rockwell B and Brinell.

Comparison tables should only be used as a guide. The figures shown are not equivalents and Righton Blackburns accepts no responsibility of the accuracy of the data. In any case of doubt or dispute values using the actual test methods should be used rather than converted table values.

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