Rockwell Hardness (HRC), Brinell Hardness (HB): Difference and Conversion

Difference and conversion of hardness comparison between Rockwell hardness (HRC) and Brinell hardness (HB)

Hardness

Hardness is a performance index used to measure the resistance of materials to indentation or deformation caused by hard objects.

There are various methods for hardness testing, each with its own principles and meaning behind the measured hardness values.

The most commonly used method is the static load indentation hardness test, which includes Brinell hardness (HB), Rockwell hardness (HRA, HRB, HRC), Vickers hardness (HV), and Shore hardness (HA, HD) for rubber and plastics.

These values indicate the material’s ability to resist indentation by hard objects.

On the other hand, the rebound hardness test includes popular methods such as Leeb hardness (HL) and Shore hardness (HS), which measure the elastic deformation work of metals.

Therefore, hardness is not simply a physical quantity, but a comprehensive performance index that reflects the elasticity, plasticity, strength, and toughness of materials.

Hardness of steel

The hardness of metals is denoted by the code H. Based on various hardness testing methods, the following classifications can be made:

● The conventional methods include Brinell (HB), Rockwell (HRC), Vickers (HV), and Leeb (HL) hardness tests. Among these, HB and HRC are more commonly used.

● HB has a wide range of applications, while HRC is suitable for materials with high surface hardness, such as those achieved through heat treatment.

The primary difference between these two tests is the type of probe used in the hardness tester. The Brinell hardness tester employs a steel ball as the probe, whereas the Rockwell hardness tester uses a diamond probe.

● HV – suitable for microscopic analysis. The Vickers hardness (HV) is measured by pressing a diamond square cone indenter with a top angle of 136° into the material surface with a load less than 120kg. The Vickers hardness value (HV) is obtained by dividing the surface area of the material indentation pit by the load value.

● The HL portable hardness tester is convenient for measurements. It works by bouncing after the impact ball head hits the hardness surface. The hardness is calculated using the ratio of the rebound speed and impact speed of the punch at 1mm from the sample surface, and the formula: Leeb hardness HL = 1000 × VB (rebound velocity) / VA (impact velocity).

● The most commonly used portable Leeb hardness tester can be converted to Brinell (HB), Rockwell (HRC), Vickers (HV), and Shore (HS) hardness after measuring with Leeb (HL). Alternatively, you can directly measure the hardness value using Brinell (HB), Rockwell (HRC), Vickers (HV), Leeb (HL), and Shore (HS) using the Leeb principle.

The TH series Leeb hardness tester, produced by Time Company, has this function, which is a useful supplement to the traditional desktop hardness machine! (For details, please click Leeb Hardness Tester TH140/TH160/HLN-11A/HS141 Portable Series).

1. HB – Brinell hardness:

Brinell hardness (HB) is typically used for soft materials, such as nonferrous metals, steel before heat treatment, or after annealing.

On the other hand, Rockwell hardness (HRC) is generally used for materials with higher hardness, such as those that have undergone heat treatment.

To measure Brinell hardness, a hardened steel ball or cemented carbide ball with a specific diameter is pressed into the surface of the material being tested under a specified test load, held for a set time, and then unloaded to measure the indentation diameter of the surface being tested.

The Brinell hardness value is calculated by dividing the load by the spherical surface area of the indentation.

Typically, a hardened steel ball with a diameter of 10mm is pressed into the material surface with a load of 3000kg for a certain duration. After unloading, the ratio of the load to the indentation area yields the Brinell hardness value (HB), measured in kilogram force per square millimeter (kgf/mm2 or N/mm2).

2. HR Rockwell hardness

Rockwell hardness (HR) is a method to determine the hardness index of a material based on the plastic deformation depth of indentation. The hardness is measured in units of 0.002 mm.

When the Brinell hardness test cannot be used, such as when the material’s HB value is greater than 450 or the sample size is too small, the Rockwell hardness test is used instead.

This test involves pressing either a diamond cone with a top angle of 120° or a steel ball with a diameter of 1.59 mm or 3.18 mm into the surface of the tested material under a specific load. The hardness of the material is then calculated from the depth of the indentation.

There are three different scales for Rockwell hardness measurements based on the hardness of the test material:

HRA: It’s a measure of hardness determined by using a diamond cone indenter and applying a 60kg load. This scale is used for materials that have extremely high hardness, such as cemented carbide.

HRB: It’s a measure of hardness determined by using a 1.59mm diameter hardened steel ball and applying a 100kg load. This scale is used for materials that have low hardness, such as annealed steel, cast iron, etc.

HRC: It’s a measure of hardness determined by using a diamond cone press and applying a 150kg load. This scale is used for materials that have high hardness, such as quenched steel, etc.

In addition:

(1) HRC stands for the Rockwell hardness C scale.

(2) HRC and HB are widely used in production.

(3) The HRC application range is from HRC 20 to 67, which is equivalent to HB225 to 650. If the hardness exceeds this range, the Rockwell hardness A scale (HRA) should be used. If the hardness is lower than this range, the Rockwell hardness B scale (HRB) should be used. The upper limit of Brinell hardness (HB650) cannot be exceeded.

(4) The indenter of the Rockwell hardness tester’s C scale is a diamond cone with a top angle of 120 degrees. The test load is a specific value, with a Chinese standard of 150 kg force.

The Brinell hardness tester uses a hardened steel ball (HBS) or cemented carbide ball (HBW) as the indenter, and the test load varies with the ball diameter, ranging from 3000 to 31.25 kgf.

(5) Rockwell hardness indentation is very small, and the measured value is localized, so it is necessary to measure the average value at several points. It is suitable for finished products and thin films and is classified as nondestructive testing.

Brinell hardness indentation is large, and the measured value is accurate. It is not suitable for finished products and thin films and is generally not considered nondestructive testing.

(6) The hardness value of Rockwell hardness is a dimensionless number and does not have a unit. Therefore, it is incorrect to refer to Rockwell hardness in terms of degrees. The hardness value of Brinell hardness has units and has an approximate relationship with tensile strength.

(7) Rockwell hardness can be displayed directly on the dial or digitally. It is easy to operate, fast, and intuitive, making it suitable for mass production. Brinell hardness requires a microscope to measure the indentation diameter and then check the table or perform calculations, which can be complicated.

(8) Under certain conditions, HB and HRC can be checked and exchanged. The mental calculation formula is roughly 1HRC ≈ 1/10HB.

The following are several common comparison tables:

1. National standard hardness HLD/HRC/HRB/HV/HB/HSD conversion table>>

2. According to the German standard DIN50150, the following is the comparison table between the tensile strength of steels in common range and Vickers hardness, Brinell hardness and Rockwell hardness:


Tensile strength
Rm N/mm2
HVHBHRC
2508076.0
2708580.7
2859085.2
3059590.2
32010095.0
33510599.8
350110105
370115109
380120114
400125119
415130124
430135128
450140133
465145138
480150143
490155147
510160152
530165156
545170162
560175166
575180171
595185176
610190181
625195185
640200190
660205195
675210199
690215204
705220209
720225214
740230219
755235223
77024022820.3
78524523321.3
80025023822.2
82025524223.1
83526024724.0
85026525224.8
86527025725.6
88027526126.4
90028026627.1
91528527127.8
93029027628.5
95029528029.2
96530028529.8
99531029531.0
103032030432.2
106033031433.3
109534032334.4
112535033335.5
111536034236.6
119037035237.7
122038036138.8
125539037139.8
129040038040.8
132041039041.8
135042039942.7
138543040943.6
142044041844.5
145545042845.3
148546043746.1
152047044746.9
1555480(456)47.7
1595490(466)48.4
1630500(475)49.1
1665510(485)49.8
1700520(494)50.5
1740530(504)51.1
1775540(513)51.7
1810550(523)52.3
1845560(532)53.0
1880570(542)53.6
1920580(551)54.1
1955590(561)54.7
1995600(570)55.2
2030610(580)55.7
2070620(589)56.3
2105630(599)56.8
2145640(608)57.3
2180650(618)57.8
 660 58.3
 670 58.8
 680 59.2
 690 59.7
 700 60.1
 720 61.0
 740 61.8
 760 62.5
 780 63.3
 800 64.0
 820 64.7
 840 65.3
 860 65.9
 880 66.4
 900 67.0
 920 67.5
 940 68.0

3. Rough relationship table of various hardness:

HBA HB HV HWB HRC
GYZJ
934-1
10mm
500kg
5kg B E F H
35   21         32
36   22         35
37   23         37
38   24         40
39   25         42
40 25 26         45
41 25 27         47
42 26 28         49
43 27 29         51
44 27 30         54
45 28 30         56
46 29 31         58
47 30 32     23   60
48 30 33 0.7   26   62
49 31 34 1.3   28   64
50 32 35 1.9   31   66
51 33 36 2.5   34   68
52 34 38 3.1   36   70
53 35 39 3.6   39 30 72
54 37 40 4.2   41 34 73
55 38 41 4.7   44 37 75
56 39 43 5.3   46 40 77
57 40 44 5.8   48 43 78
58 42 45 6.3   50 46 80
59 43 47 6.8   53 48 82
60 45 49 7.3   55 51 83
61 46 50 7.8   57 54 85
62 48 52 8.3   59 56 86
63 50 54 8.8   61 59 88
64 51 56 9.2   63 61 89
65 53 58 9.7   65 63 90
66 55 60 10.1   67 66 92
67 57 62 10.6   69 68 93
68 60 65 11   71 70 94
69 62 67 11.4   73 72 95
70 64 70 11.8 17 75 74 97
71 67 72 12.2 23 76 75 98
72 69 75 12.6 28 78 77 99
73 72 78 12.9 33 80 79 100
74 75 81 13.3 38 81 80 101
75 78 85 13.7 42 83 82 102
76 80 88 14 47 84 83 103
77 84 92 14.3 51 86 85 104
78 87 95 14.7 55 87 86 105
79 90 99 15 59 89 88 106
80 94 103 15.3 63 90 89 106
81 97 108 15.6 66 91 90 107
82 101 112 15.9 70 92 91 108
83 105 117 16.2 73 94 92 109
84 109 121 16.4 76 95 93 109
85 113 126 16.7 79 96 94 110
86 117 131 16.9 81 97 95 111
87 121 137 17.2 84 98 96 111
88 126 142 17.4 86 99 97 112
89 130   17.6 88 100 98 112
90 135   17.8 90 101 98 113
91 140   18   102 99 114
92 145   18.2   103 100  
93     18.4   103 100  
94     18.6   104 101  
95     18.7   105 102  
96     18.9   106 102  
97     19   106 103  
98     19.2   107    
98     19.3   107    
100     19.4   108    

Note: Table 3 source: Baber Colman

4. Approximate conversion value of Brinell hardness of steel

Brinell hardness (HB)
10mm 3000kgf
Vickers hardness
(HV)
Rockwell hardness Shore hardness
(HS)
Tensile strength
(approx.) MPa
Standard ball Tungsten carbide ball Load 60kgf
(HRA)
Load 100kgf
(HRB)
Load 100kgf
(HRC)
Load 150kgf
(HRD)
940 85.6 68 76.9 97
920 85.3 67.5 76.5 96
900 85 67 76.1 95
-767 880 84.7 66.4 75.7 93
-757 860 84.4 65.9 75.3 92
                 
-745 840 84.1 65.3 74.8 91
-733 820 83.8 64.7 74.3 90
-722 800 83.4 64 73.8 88
-712
-710 780 83 63.3 73.3 87
-698 760 82.6 62.5 72.6 86
                 
-684 740 82.2 61.8 72.1
-682 737 82.2 61.7 72 84
-670 720 81.8 61 71.5 83
-656 700 81.3 60.1 70.8
-653 697 81.2 60 70.7 81
                 
-647 690 81.1 59.7 70.5
-638 680 80.8 59.2 70.1 80
630 670 80.6 58.8 69.8
627 667 80.5 58.7 69.7 79
                 
677 80.7 59.1 70
601 640 79.8 57.3 68.7 77
                 
640 79.8 57.3 68.7
578 615 79.1 56 67.7 75
                 
607 78.8 55.6 67.4
555 591 78.4 54.7 66.7 73 2055
                 
579 78 54 66.1 2015
534 569 77.8 53.5 65.8 71 1985
                 
533 77.1 52.5 65 1915
514 547 76.9 52.1 64.7 70 1890
                 
-495 539 76.7 51.6 64.3 1855
530 76.4 51.1 63.9 1825
495 528 76.3 51 63.8 68 1820
                 
-477 516 75.9 50.3 63.2 1780
508 75.6 49.6 62.7 1740
477 508 75.6 49.6 62.7 66 1740
                 
-461 495 75.1 48.8 61.9 1680
491 74.9 48.5 61.7 1670
461 491 74.9 48.5 61.7 65 1670
                 
444 474 74.3 47.2 61 1595
472 74.2 47.1 60.8 1585
444 472 74.2 47.1 60.8 63 1585
                 
429 429 455 73.4 45.7 59.7 61 1510
415 415 440 72.8 44.5 58.8 59 1460
401 401 425 72 43.1 57.8 58 1390
388 388 410 71.4 41.8 56.8 56 1330
375 375 396 70.6 40.4 55.7 54 1270
                 
363 363 383 70 39.1 54.6 52 1220
352 352 372 69.3 -110 37.9 53.8 51 1180
341 341 360 68.7 -109 36.6 52.8 50 1130
331 331 350 68.1 -108.5 35.5 51.9 48 1095
321 321 339 67.5 -108 34.3 51 47 1060
                 
311 311 328 66.9 -107.5 33.1 50 46 1025
302 302 319 66.3 -107 32.1 49.3 45 1005
293 293 309 65.7 -106 30.9 48.3 43 970
285 285 301 65.3 -105.5 29.9 47.6 950
277 277 292 64.6 -104.5 28.8 46.7 41 925
                 
269 269 284 64.1 -104 27.6 45.9 40 895
262 262 276 63.6 -103 26.6 45 39 875
255 255 269 63 -102 25.4 44.2 38 850
248 248 261 62.5 -101 24.2 43.2 37 825
241 241 253 61.8 100 22.8 42 36 800
                  
235 235 247 61.4 99 21.7 41.4 35 785
229 229 241 60.8 98.2 20.5 40.5 34 765
223 223 234 97.3 -18.8  
217 217 228 96.4 -17.5 33 725
212 212 222 95.5 -16 705
                 
207 207 218 94.6 -15.2 32 690
201 201 212 93.8 -13.8 31 675
197 197 207 92.8 -12.7 30 655
192 192 202 91.9 -11.5 29 640
187 187 196 90.7 -10 620
                 
183 183 192 90 -9 28 615
179 179 188 89 -8 27 600
174 174 182 87.8 -6.4 585
170 170 178 86.8 -5.4 26 570
167 167 175 86 -4.4 560
                 
163 163 171 85 -3.3 25 545
156 156 163 82.9 -0.9 525
149 149 156 80.8 23 505
143 143 150 78.7 22 490
137 137 143 76.4 21 460
                 
131 131 137 74 450
126 126 132 72 20 435
121 121 127 69.8 19 415
116 116 122 67.6 18 400
111 111 117 65.7 15 385

The hardness test is a simple and easy method to test mechanical properties.

To substitute some mechanical property tests with hardness tests, a more accurate conversion relationship between hardness and strength is required in production.

Empirical evidence has shown that there is an approximate correlation between the various hardness values of metal materials, as well as between hardness and strength values.

Since the hardness value is determined by both the initial and continuous plastic deformation resistance, a material with higher strength will exhibit higher plastic deformation resistance and therefore higher hardness values.

National Standard Hardness HLD/HRC/HRB/HV/HB/HSD Conversion Table

HLDHRCHRBHVHB[1]HB[2]HSDHLDHRCHRBHVHB[1]HB[2]HSD
300  83   59633.9 32231431546.3
302  84   59834.2 32531631846.6
304  85   60034.5 32831932046.9
306  85   60234.8 33032232347.2
308  86   60435.1 33332432547.5
310  87   60635.4 33632732847.8
312  87   60835.7 33833033148.2
314  88   61035.9 34133233348.5
316  89   61236.2 34433533648.8
318  90   61436.5 34633833949.1
320  90   61636.8 34934034149.4
322  91   61837.1 35234334449.7
324  92   62037.4 35534634650.1
326  93   62237.6 35734934950.4
328  94   62437.9 36035135250.7
330  94   62638.2 36335435551
332  95   62838.5 36635735751.3
334  96   63038.7 36936036051.7
336  97   63239 37236336352
338  98   63439.3 37536636652.3
340  99   63639.6 37736936952.6
342  100   63839.8 38037137152.9
344  101   64040.1 38337437453.3
346  101   64240.4 38637737753.6
348  102   64440.7 38938038053.9
350 59.6103   64640.9 39238338354.2
352 60.3104   64841.2 39538638654.6
354 61105   65041.5 39838938954.9
356 61.7106   65241.7 40139239255.2
358 62.4107   65442 40439539555.6
360 63.1108   65642.3 40739839855.8
362 63.8109   65842.6 41140140156.2
364 64.5110   66042.8 41440440456.5
366 65.1111   66243.1 41740740756.9
368 65.8112   66443.4 42041041057.2
370 66.4114   66643.6 42341341357.5
372 67115   66843.9 42641741757.9
374 67.7116   67044.1 42942042058.2
376 68.3117   67244.4 43342342358.5
378 68.9118   67444.7 43642642658.9
380 69.5119   67644.9 43942942959.2
382 70.1120   67845.2 44243243259.5
384 70.6121   68045.5 44643543559.9
386 71.2123   68245.7 44943943960.2
388 71.8124   68446 45244244260.5
390 72.3125   68646.2 45644544560.9
392 72.9126   68846.5 45944844861.2
394 73.4127   69046.8 46345145161.6
396 74129   69247 46645545561.9
398 74.5130   69447.3 46945845862.2
400 75131 142 69647.5 47346146162.6
402 75.5133 144 69847.8 47646546562.9
404 76134 145 70048 48046846863.3
406 76.5135 147 70248.3 48347147163.6
408 77136 149 70448.6 48747447464
410 77.5138 150 70648.8 49147847864.3
412 78139 152 70849.1 49448148164.6
414 78.4141 153 71049.3 49848548565
416 78.9142 155 71249.6 50148848865.3
418 79.3143 156 71449.8 50549149165.7
420 79.8145140157 71650.1 50949549566
422 80.2146141159 71850.3 51349849866.4
424 80.7148143160 72050.6 51650250266.7
426 81.1149144162 72250.8 52050550567.1
428 81.5151145163 72451.1 52450850867.4
430 81.9152147165 72651.3 52851251267.8
432 82.4154148166 72851.6 53251551568.2
434 82.8155150168 73051.8 53551951968.5
436 83.2157151169 73252.1 53952252268.9
438 83.6158153171 73452.3 54352652669.2
440 84160154172 73652.6 54752952969.6
442 84.4161156174 73852.8 55153353369.9
444 84.8163157175 74053.1 55553653670.3
446 85.1164159176 74253.3 55954054070.7
448 85.5166160178 74453.6 56354354371
450 85.9168162179 74653.8 56854754771.4
452 86.3169164181 74854.1 57255155171.8
454 86.6171165182 75054.3 57655455472.1
456 87173167184 75254.5 58055855872.5
458 87.4174168185 75454.8 58456156172.9
460 87.717617018726.475655 58956556573.2
462 88.117817218826.775855.3 59356956973.6
464 88.51791731902776055.5 59757257274
466 88.818117519127.376255.7 60257657674.3
468 89.218317719327.676456 60658058074.7
470 89.518517819427.976656.2 61058358375.1
472 89.918618019628.276856.5 61558758775.5
474 90.318818219728.577056.7 61959159175.8
476 90.619018419828.877256.9 62459459476.2
478 9119218520029.177457.2 62859859876.6
480 91.319418720229.477657.4 63360260277
482 91.719518920329.777857.6 63860560577.4
484 92.11971912053078057.9 64260960977.7
486 92.419919220630.378258.1 64761361378.1
488 92.820119420830.678458.3 65261761778.5
490 93.120319620930.978658.6 65762062078.9
492 93.520519821131.278858.8 66262462479.3
494 93.920720021231.579059 66662862879.7
496 94.320920221431.779259.2 67163263280.1
498 94.62112042153279459.5 67663563580.5
500 9521320521732.279659.7 68163963980.9
502 95.421520721932.579859.9 68664364381.2
504 95.821720922032.880060.1 69164764781.6
506 96.221921122233.180260.4 69765165182
508 96.622121322433.380460.6 702  82.4
51019.89722321522533.680660.8 707  82.8
51220.297.422521722733.980861 712  83.2
51420.697.922721922934.281061.2 718  83.7
5162198.322922123034.481261.4 723  84.1
51821.398.723122323234.781461.7 728  84.5
52021.799.22332252343581661.9 734  84.9
5222299.623522723535.381862.1 739  85.3
52422.4 23722923735.682062.3 745  85.7
52622.8 23923123935.882262.5 750  86.1
52823.1 24123424136.182462.7 756  86.5
53023.5 24423624236.482662.9 762  87
53223.8 24623824436.782863.1 768  87.4
53424.1 2482402463783063.3 773  87.8
53624.5 25024224837.383263.5 779  88.2
53824.8 25224425037.683463.7 785  88.6
54025.2 25524625237.983663.9 791  89.1
54225.5 25724925438.183864.1 797  89.5
54425.8 25925125638.484064.3 803  89.9
54626.2 26125325838.784264.5 809  90.4
54826.5 2642552593984464.7 816  90.8
55026.8 26625826139.384664.9 822  91.2
55227.1 26826226339.684865.1 828  91.7
55427.5 27026226539.985065.3 835  92.1
55627.8 27326526840.285265.4 841  92.6
55828.1 27526727040.585465.6 848  93
56028.4 27826927240.885665.8 854  93.5
56228.8 28027227441.185866 861  93.9
56429.1 28227427641.486066.2 867  94.4
56629.4 28527627841.786266.3 874  94.8
56829.7 2872792804286466.5 881  95.3
57030 29028128242.386666.7 888  95.7
57230.3 29228328542.686866.8 895  96.2
57430.6 29428628742.987067 902  96.7
57630.9 29728828943.287267.2 909  97.1
57831.2 29929129243.587467.3 916  97.6
58031.5 30229329443.887667.5 923  98.1
58231.8 30429629644.187867.6 931  98.6
58432.1 30729829944.488067.8 938  99
58632.4 30930130144.788268 946  99.5
58832.7 3123033044588468.1 953   
59033 31530630845.488668.2 961   
59233.3 31730831045.788868.4 968   
59433.6 3203113134689068.5 976   

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