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Hardness Conversion Chart

Rockwell C & B, Vickers, Brinell, and approximate tensile strength — converted from Mitutoyo Bulletin 2059(2).

True Precision Machining
Dual-scale hardness bar, drawn to scale and linear in Rockwell C: a sectioned steel bar with HRC graduations 20, 30, 40, 50, 60, and 65 on top and the equivalent Vickers values 238, 302, 392, 513, 697, and 832 HV under each graduation. Red markers above the bar locate mild steel below 20 HRC, prehard 4140 at 28 to 32, 17-4PH H900 at 40 to 44, hardened tool steel at 60 to 62, and a file near 65. Equal 10-point HRC steps stretch from 64 HV at the soft end to 184 HV at the hard end. MILD STEEL <20 HRC 17-4PH H900 40–44 HRC FILE ~65 HRC 4140 PREHARD 28–32 HRC HARDENED TOOL STEEL 60–62 HRC 20 238 30 302 40 392 50 513 60 697 65 832 HRC HV 10 HRC = 64 HV 10 HRC = 184 HV EQUAL HRC STEPS STRETCH IN HV → ONE HARDNESS — TWO SCALES Conversions from Mitutoyo Bulletin 2059(2) (steel) — approximate by definition. Spec ONE scale on the drawing; convert for reference only.
Rockwell Vickers Brinell Approx. tensile · steel
HRC HRB HV HB UTS ksi UTS MPa
68 — 940 — — —
65 — 832 739 — —
62 — 746 688 — —
60 — 697 654 — —
58 — 653 615 338 2330
56 — 613 577 313 2158
54 — 577 543 292 2013
52 — 544 512 273 1882
50 — 513 481 255 1758
48 — 484 455 238 1641
46 — 458 432 221 1524
44 — 434 409 208 1434
42 — 412 390 194 1338
40 — 392 371 182 1255
38 — 372 353 171 1179
36 — 354 336 161 1110
34 — 336 319 152 1048
32 — 318 301 146 1007
30 — 302 286 138 951
28 — 286 271 131 903
26 — 272 258 125 862
24 — 260 247 119 820
22 — 248 237 115 793
20 — 238 226 110 758
— 98 — 228 109 752
— 95 — 210 100 689
— 92 — 195 92 634
— 90 — 185 89 614
— 86 — 169 83 572
— 80 — 150 72 496
— 75 — 137 66 455
— 70 — 125 61 421
— 60 — 107 — —
— 50 — — — —

Key: bold = primary scales (HRC · HRB · HV)  ·  — = outside that scale’s usable range  ·  UTS = estimate from hardness, steel only

HRC — Rockwell C, diamond cone / 150 kgf. Hardened steel ≥ 20 HRC (tool steel, hardened 4140/4340, 17-4PH H900–H1075).

HRB — Rockwell B, 1/16″ ball / 100 kgf. Annealed steel, brass, aluminum bronze, hard plastics. Above ~100 HRB switch to HRC.

HV — Vickers, diamond pyramid / variable load. One scale from soft aluminum to carbide; thin coatings and case-depth work.

HB — Brinell, 10 mm ball / 3000 kgf for steel. Large indent averages non-uniform material — castings, forgings.

Approximate values from Mitutoyo Bulletin 2059(2), July 2017. HB uses the source's 3000 kgf / 10 mm ball column. No carbide-ball test equivalence is implied. HRB-region HV values are withheld: the source has a separate Knoop column and a combined HB/HV heading, not a separately identified Vickers test column. Tensile columns are approximate steel correlations, not test results or design allowables. A dash means unavailable in the source. Non-steel conversions require material-specific data. See the hardness conversion reference.

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trueprecisionmachining.com · 805-964-4545 · Buellton, CA · AS9100 / ISO 9001 / ITAR
Approximate conversions for steel from Mitutoyo Bulletin 2059(2) — verify against material-specific data for non-steel or design-critical work. · September 2026