ASTM E140 - 12b - Table 1: Approximate Hardness Conversion Numbers for Non-Austenitic Steels (Rockwell C Hardness Range)A, B

Note: These conversions are approximate and based on ASTM E140 standard for steel materials. Actual conversions may vary depending on material composition and heat treatment. Reference material: ASTM E140 - 12b (Link: https://store.astm.org/e0140-12b.html), version editorially corrected in August 2013.

Rockwell C Hardness Number 150 kgf (HRC) Vickers Hardness Number (HV) Brinell Hardness NumberC Knoop Hardness, Number 500-gf and Over (HK) Rockwell Hardness Number Rockwell Superficial Hardness Number Scleroscope Hardness NumberD Rockwell C Hardness Number 150 kgf (HRC)
10-mm Standard Ball, 3000-kgf (HBS) 10-mm Carbide Ball, 3000-kgf (HBW) A Scale, 60-kgf (HRA) D Scale, 100-kgf (HRD) 15-N Scale, 15-kgf (HR 15-N) 30-N Scale, 30-kgf (HR 30-N) 45-N Scale, 45-kgf (HR 45-N)
68 940 ... ... 920 85.6 76.9 93.2 84.4 75.4 97.3 68
67 900 ... ... 895 85.0 76.1 92.9 83.6 74.2 95.0 67
66 865 ... ... 870 84.5 75.4 92.5 82.8 73.3 92.7 66
65 832 ... (739) 846 83.9 74.5 92.2 81.9 72.0 90.6 65
64 800 ... (722) 822 83.4 73.8 91.8 81.1 71.0 88.5 64
63 772 ... (705) 799 82.8 73.0 91.4 80.1 69.9 86.5 63
62 746 ... (688) 776 82.3 72.2 91.1 79.3 68.8 84.5 62
61 720 ... (670) 754 81.8 71.5 90.7 78.4 67.7 82.6 61
60 697 ... (654) 732 81.2 70.7 90.2 77.5 66.6 80.8 60
59 674 ... 634 710 80.7 69.9 89.8 76.6 65.5 79.0 59
58 653 ... 615 690 80.1 69.2 89.3 75.7 64.3 77.3 58
57 633 ... 595 670 79.6 68.5 88.9 74.8 63.2 75.6 57
56 613 ... 577 650 79.0 67.7 88.3 73.9 62.0 74.0 56
55 595 ... 560 630 78.5 66.9 87.9 73.0 60.9 72.4 55
54 577 ... 543 612 78.0 66.1 87.4 72.0 59.8 70.9 54
53 560 ... 525 594 77.4 65.4 86.9 71.2 58.6 69.4 53
52 544 (500) 512) 576 76.8 64.6 86.4 70.2 57.4 67.9 52
51 528 (487) 496 558 76.3 63.8 85.9 69.4 56.1 66.5 51
50 513 (475) 481 542 75.9 63.1 85.5 68.5 55.0 65.1 50
49 498 (464) 469 526 75.2 62.1 85.0 67.6 53.8 63.7 49
48 484 451 455 510 74.7 61.4 84.5 66.7 52.5 62.4 48
47 471 442 443 495 74.1 60.8 83.9 65.8 51.4 61.1 47
46 458 432 432 480 73.6 60.0 83.5 64.8 50.3 59.8 46
45 446 421 421 466 73.1 59.2 83.0 64.0 49.0 58.5 45
44 434 409 409 452 72.5 58.5 82.5 63.1 47.8 57.3 44
43 423 400 400 438 72.0 57.7 82.0 62.2 46.7 56.1 43
42 412 390 390 428 71.5 56.9 81.5 61.3 45.5 54.9 42
41 402 381 381 414 70.9 56.2 80.9 60.4 44.3 53.7 41
40 392 371 371 402 70.4 55.4 80.4 59.5 43.1 52.6 40
39 382 362 362 391 69.9 54.6 79.9 58.6 41.9 51.5 39
38 372 353 353 380 69.4 53.8 79.4 57.7 40.8 50.4 38
37 363 344 344 370 68.9 53.1 78.8 56.8 39.6 49.3 37
36 354 336 336 360 68.4 52.3 78.3 55.9 38.4 48.2 36
35 345 327 327 351 67.9 51.5 77.7 55.0 37.2 47.1 35
34 336 319 319 342 67.4 50.8 77.2 54.2 36.1 46.1 34
33 327 311 311 334 66.8 50.0 76.6 53.3 34.9 45.1 33
32 318 301 301 326 66.3 49.2 76.1 52.1 33.7 44.1 32
31 310 294 294 318 65.8 48.4 75.6 51.3 32.5 43.1 31
30 302 286 286 311 65.3 47.7 75.0 50.4 31.3 42.2 30
29 294 279 279 304 64.8 47.0 74.5 49.5 30.1 41.3 29
28 286 271 271 297 64.3 46.1 73.9 48.6 28.9 40.4 28
27 279 264 264 290 63.8 45.2 73.3 47.7 27.8 39.5 27
26 272 258 258 284 63.3 44.6 72.8 46.8 26.7 38.7 26
25 266 253 253 278 62.8 43.8 72.2 45.9 25.5 37.8 25
24 260 247 247 272 62.4 43.1 71.6 45.0 24.3 37.0 24
23 254 243 243 266 62.0 42.1 71.0 44.0 23.1 36.3 23
22 248 237 237 261 61.5 41.6 70.5 43.2 22.0 35.5 22
21 243 231 231 256 61.0 40.9 69.9 42.3 20.7 34.8 21
20 238 226 226 251 60.5 40.1 69.4 41.5 19.6 34.2 20

Standards Reference: ASTM E140 - Standard Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, Scleroscope Hardness, and Leeb Hardness.

A: In the table headings, force refers to total test forces.

B: Annex A1 (in the reference paper) contains equations converting determined hardness scale numbers to Rockwell C hardness numbers for non-austenitic steels. Refer to 1.12 before using conversion equations.

C: The Brinell hardness numbers in parentheses are outside the range recommended for Brinell hardness testing in 8.1 of Test Method E10.

D: These Scleroscope hardness conversions are based on Vickers-Scleroscope hardness relationships developed from Vickers hardness data provided by the National Bureau of Standards for 13 steel reference blocks, Scleroscope hardness values obtained on these blocks by the Shore Instrument and Mfg. Co., Inc., the Roll Manufacturers Institute, and members of this institute, and also on hardness conversions previously published by the American Society for Metals and the Roll Manufacturers Institute.

ASTM E140 - 12b - Table 2: Approximate Hardness Conversion Numbers for Non-Austenitic Steels (Rockwell B Hardness Range)A, B

Note: These conversions are approximate and based on ASTM E140 standard for steel materials. Actual conversions may vary depending on material composition and heat treatment. Reference material: ASTM E140 - 12b (Link: https://store.astm.org/e0140-12b.html), version editorially corrected in August 2013.

Rockwell B Hardness Number, 100-kgf (HRB) Vickers Hardness Number (HV) Brinell Hardness Number, 3000-kgf, (HBS) Knoop Hardness Number, 500-gf, and Over (HK) Rockwell A Hardness Number, 60-kgf. (HRA) Rockwell F Hardness Number, 60-kgt, (HRF) Rockwell Superficial Hardness Number Rockwell B Hardness Number, 100-kgf, (HRB)
15-T Scale, 15-kgf, (HR 15-T) 30-T Scale, 30-kgf, (HR 30-T) 45-T Scale, 45-kgf, (HR 45-T)
100 240 240 251 61.5 ... 93.1 83.1 72.9 100
99 234 234 246 60.9 ... 92.8 82.5 71.9 99
98 228 228 241 60.2 ... 92.5 81.8 70.9 98
97 222 222 236 59.5 ... 92.1 81.1 69.9 97
96 216 216 231 58.9 ... 91.8 80.4 68.9 96
95 210 210 226 58.3 ... 91.5 79.8 67.9 95
94 205 205 221 57.6 ... 91.2 79.1 66.9 94
93 200 200 216 57.0 ... 90.8 78.4 65.9 93
92 195 195 211 56.4 ... 90.5 77.8 64.8 92
91 190 190 206 55.8 ... 90.2 77.1 63.8 91
90 185 185 201 55.2 ... 89.9 76.4 62.8 90
89 180 180 196 54.6 ... 89.5 75.8 61.8 89
88 176 176 192 54.0 ... 89.2 75.1 60.8 88
87 172 172 188 53.4 ... 88.9 74.4 59.8 87
86 169 169 184 52.8 ... 88.6 73.8 58.8 86
85 165 165 180 52.3 ... 88.2 73.1 57.8 85
84 162 162 176 51.7 ... 87.9 72.4 56.8 84
83 159 159 173 51.1 ... 87.6 71.8 55.8 83
82 156 156 170 50.6 ... 87.3 71.1 54.8 82
81 153 153 167 50.0 ... 86.9 70.4 53.8 81
80 150 150 164 49.5 ... 86.6 69.7 52.8 80
79 147 147 161 48.9 ... 86.3 69.1 51.8 79
78 144 144 158 48.4 ... 86.0 68.4 50.8 78
77 141 141 155 47.9 ... 85.6 67.7 49.8 77
76 139 139 152 47.3 ... 85.3 67.1 48.8 76
75 137 137 150 46.8 99.6 85.0 66.4 47.8 75
74 135 135 147 46.3 99.1 84.7 65.7 46.8 74
73 132 132 145 45.8 98.5 84.3 65.1 45.8 73
72 130 130 143 45.3 98.0 84.0 64.4 44.8 72
71 127 127 141 44.8 97.4 83.7 63.7 43.8 71
69 123 123 137 43.8 96.2 83.0 62.4 41.8 69
68 121 121 135 43.3 95.6 82.7 61.7 40.8 68
67 119 119 133 42.8 95.1 82.4 61.0 39.8 67
66 117 117 131 42.3 94.5 82.1 60.4 38.7 66
65 116 116 129 41.8 93.9 81.8 59.7 37.7 65
64 114 114 127 41.4 93.4 81.4 59.0 36.7 64
63 112 112 125 40.9 92.8 81.1 58.4 35.7 63
62 110 110 124 40.4 92.2 80.8 57.7 34.7 62
61 108 108 122 40.0 91.7 80.5 57.0 33.7 61
60 107 107 120 39.5 91.1 80.1 56.4 32.7 60
59 106 106 118 39.0 90.5 79.8 55.7 31.7 59
58 104 104 117 38.6 90.0 79.5 55.0 30.7 58
57 103 103 115 38.1 89.4 79.2 54.4 29.7 57
56 101 101 114 37.7 88.8 78.8 53.7 28.7 56
55 100 100 112 37.2 88.2 78.5 53.0 27.7 55
54 ... ... 111 36.8 87.7 78.2 52.4 26.7 54
53 ... ... 110 36.3 87.1 77.9 51.7 25.7 53
52 ... ... 109 35.9 86.5 77.5 51.0 24.7 52
51 ... ... 108 35.5 86.0 77.2 50.3 23.7 51
50 ... ... 107 35.0 85.4 76.9 49.7 22.7 50
49 ... ... 106 34.6 84.8 76.6 49.0 21.7 49
48 ... ... 105 34.1 84.3 76.2 48.3 20.7 48
47 ... ... 104 33.7 83.7 75.9 47.7 19.7 47
46 ... ... 103 33.3 83.1 75.6 47.0 18.7 46
45 ... ... 102 32.9 82.6 75.3 46.3 17.7 45
44 ... ... 101 32.4 82.0 74.9 45.7 16.7 44
43 ... ... 100 32.0 81.4 74.6 45.0 15.7 43
42 ... ... 99 31.6 80.8 74.3 44.3 14.7 42
41 ... ... 98 31.2 80.3 74.0 43.7 13.6 41
40 ... ... 97 30.7 79.7 73.6 43.0 12.6 40
39 ... ... 96 30.3 79.1 73.3 42.3 11.6 39
38 ... ... 95 29.9 78.6 73.0 41.6 10.6 38
37 ... ... 94 29.5 78.0 72.7 41.0 9.6 37
36 ... ... 93 29.1 77.4 72.3 40.3 8.6 36
35 ... ... 92 28.7 76.9 72.0 39.6 7.6 35
34 ... ... 91 28.2 76.3 71.7 39.0 6.6 34
33 ... ... 90 27.8 75.7 71.4 38.3 5.6 33
32 ... ... 89 27.4 75.2 71.0 37.6 4.6 32
31 ... ... 88 27.0 74.6 70.7 37.0 3.6 31
30 ... ... 87 26.6 74.0 70.4 36.3 2.6 30

Standards Reference: ASTM E140 - Standard Hardness Conversion Tables for Metals Relationship Among Brinell Hardness, Vickers Hardness, Rockwell Hardness, Superficial Hardness, Knoop Hardness, Scleroscope Hardness, and Leeb Hardness

A: In the table headings, kgf refers to total test force.

B: Annex A2 (in the reference paper) contains equations converting determined hardness numbers to Rockwell B hardness numbers for non-austenitic steels. Refer to 1.12 before using conversion equations.

Fundamental Hardness Equations

Vickers Hardness

HV = 1.854 × F/d²

Where: F = applied force (kg), d = diagonal length of indentation (mm)

Brinell Hardness

HB = 2F / (πD(D - √(D² - d²)))

Where: F = force (kg), D = ball diameter (mm), d = indentation diameter (mm)

Meyer Hardness Law

F = ad^n

Where: F = load, d = indentation size, a = constant, n = Meyer index (2-2.5)

Elastic Modulus Relationship

E ≈ 3H (for metals)

Approximate relationship between elastic modulus (E) and hardness (H)

Hardness Scale Definitions

Vickers Hardness (HV)

Uses a diamond pyramid indenter with 136° angle between faces, suitable for all materials and thicknesses.

Indenter: Diamond pyramid with square base

Load Range: 1 gf to 120 kgf (0.01 N to 1200 N)

Measurement: Diagonal length of square indentation

Advantages: Wide hardness range, small indentation, precise

Applications: Research, quality control, thin materials

Brinell Hardness (HB)

Uses a hardened steel or carbide ball to create a spherical indentation, good for coarse materials.

Indenter: 10mm steel or carbide ball (standard)

Load: 3000 kgf for steel, 500 kgf for softer materials

Measurement: Diameter of spherical indentation

Range: 20-650 HB typical range

Applications: Castings, forgings, large grain materials

Rockwell Hardness (HR)

Multiple scales using different indenters and loads, providing rapid testing with direct readout.

Rockwell C (HRC): Diamond cone, 150 kgf, for hard steels

Rockwell B (HRB): 1/16" ball, 100 kgf, for softer materials

Rockwell A (HRA): Diamond cone, 60 kgf, for very hard materials

Measurement: Depth of indentation under load

Advantages: Fast, direct reading, minimal operator influence

Shore Hardness (Shore A/D)

Durometer hardness for elastomers and plastics using spring-loaded indenters.

Shore A: Soft rubbers, elastomers (0-100 scale)

Shore D: Hard rubbers, rigid plastics (0-100 scale)

Indenter: Truncated cone or sphere with spring load

Measurement: Penetration depth resistance

Applications: Rubber, plastic, polymer industries

Knoop Hardness

Microhardness test using elongated diamond pyramid, ideal for brittle materials and coatings.

Indenter: Elongated diamond pyramid (7:1 ratio)

Load Range: 1-1000 gf typical

Measurement: Long diagonal of rhombic indentation

Applications: Thin coatings, ceramics, glass, brittle materials

Leeb Hardness

Portable rebound hardness test measuring impact velocity ratio, suitable for large parts.

Principle: Impact body with carbide ball rebounds from surface

Measurement: Velocity ratio (rebound/impact) × 1000

Advantages: Portable, non-destructive, large parts

Applications: Field testing, installed machinery, large components

Scientific Applications

Materials Science & Engineering

Alloy Development: Correlation with strength, wear resistance

Heat Treatment: Monitoring hardness changes during processing

Phase Analysis: Identifying microstructural changes

Manufacturing & Quality Control

Production Monitoring: Ensuring consistent material properties

Tool Selection: Matching cutting tools to material hardness

Surface Treatments: Evaluating coating effectiveness

Mechanical Design

Component Selection: Matching hardness to application requirements

Wear Prediction: Estimating component life and maintenance intervals

Contact Mechanics: Calculating contact stresses and deformation

Failure Analysis

Root Cause Investigation: Identifying material property deviations

Forensic Engineering: Determining failure mechanisms

Damage Assessment: Evaluating service-induced changes

Research & Development

New Material Characterization: Establishing property databases

Processing Optimization: Correlating process parameters with properties

Comparative Studies: Benchmarking against existing materials

Specialized Applications

Welding: Heat-affected zone analysis

Tribology: Wear and friction studies

Biomaterials: Implant and device property verification

Reference Hardness Values

Material Vickers (HV) Brinell (HB) Rockwell C (HRC) Applications
Pure Aluminum 15-20 15-20 N/A Electrical, packaging
Mild Steel 120-180 120-180 N/A Construction, automotive
Stainless Steel 316 200-250 200-250 N/A Chemical, medical
Tool Steel (annealed) 200-250 200-250 N/A Machining, forming
Tool Steel (hardened) 700-900 N/A 58-65 Cutting tools, dies
Hardened Bearing Steel 800-900 N/A 60-66 Ball bearings, races
Tungsten Carbide 1500-2000 N/A 68-72 Cutting inserts, wear parts
Sapphire 2000-2300 N/A N/A Optical windows, substrates
Diamond 8000-10000 N/A N/A Cutting tools, abrasives

Testing Considerations

Sample Preparation

Surface Finish: Smooth, clean surface free from oxidation and contamination

Sample Thickness: Minimum 2.5× indentation diagonal (Vickers/Knoop)

Support: Rigid backing to prevent deformation during testing

Test Parameters

Load Selection: Appropriate force based on material and expected hardness

Dwell Time: Standardized holding time for consistent results

Spacing: Adequate distance between indentations to avoid interference

Measurement Accuracy

Calibration: Regular verification with certified reference materials

Operator Training: Consistent technique for manual measurements

Environmental Control: Temperature and vibration effects on precision

Statistical Analysis: Multiple measurements for reliable results