HRC vs HB Hardness: Differences and Conversion

Have you ever wondered about the difference between Rockwell and Brinell hardness scales? In this article, we’ll dive into the world of material hardness testing, exploring the key distinctions between these two widely used methods. Our expert mechanical engineer will guide you through the fundamentals, providing insights into their applications and the conversion process. Get ready to expand your knowledge and gain a deeper understanding of this crucial aspect of material science.

Table Of Contents

What Is 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

Rough relationship table of various hardness

HBAHBHVHWBHRC
GYZJ
934-1
10mm
500kg
5kgBEFH
35 21    32
36 22    35
37 23    37
38 24    40
39 25    42
402526    45
412527    47
422628    49
432729    51
442730    54
452830    56
462931    58
473032  23 60
4830330.7 26 62
4931341.3 28 64
5032351.9 31 66
5133362.5 34 68
5234383.1 36 70
5335393.6 393072
5437404.2 413473
5538414.7 443775
5639435.3 464077
5740445.8 484378
5842456.3 504680
5943476.8 534882
6045497.3 555183
6146507.8 575485
6248528.3 595686
6350548.8 615988
6451569.2 636189
6553589.7 656390
66556010.1 676692
67576210.6 696893
68606511 717094
69626711.4 737295
70647011.817757497
71677212.223767598
72697512.628787799
73727812.9338079100
74758113.3388180101
75788513.7428382102
76808814478483103
77849214.3518685104
78879514.7558786105
79909915598988106
809410315.3639089106
819710815.6669190107
8210111215.9709291108
8310511716.2739492109
8410912116.4769593109
8511312616.7799694110
8611713116.9819795111
8712113717.2849896111
8812614217.4869997112
89130 17.68810098112
90135 17.89010198113
91140 18 10299114
92145 18.2 103100 
93  18.4 103100 
94  18.6 104101 
95  18.7 105102 
96  18.9 106102 
97  19 106103 
98  19.2 107  
98  19.3 107  
100  19.4 108  

Note: Table 3 source: Baber Colman

Approximate conversion value of Brinell hardness of steel

Brinell hardness (HB)
10mm
3000kgf
Vickers hardness
(HV)
Rockwell hardnessShore hardness
(HS)
Tensile strength
(approx.) MPa
Standard ballTungsten carbide ballLoad
60kgf
(HRA)
Load
100kgf
(HRB)
Load
100kgf
(HRC)
Load
150kgf
(HRD)
94085.66876.997
92085.367.576.596
900856776.195
-76788084.766.475.793
-75786084.465.975.392
         
-74584084.165.374.891
-73382083.864.774.390
-72280083.46473.888
-712
-7107808363.373.387
-69876082.662.572.686
         
-68474082.261.872.1
-68273782.261.77284
-67072081.86171.583
-65670081.360.170.8
-65369781.26070.781
         
-64769081.159.770.5
-63868080.859.270.180
63067080.658.869.8
62766780.558.769.779
         
67780.759.170
60164079.857.368.777
         
64079.857.368.7
57861579.15667.775
         
60778.855.667.4
55559178.454.766.7732055
         
579785466.12015
53456977.853.565.8711985
         
53377.152.5651915
51454776.952.164.7701890
         
-49553976.751.664.31855
53076.451.163.91825
49552876.35163.8681820
         
-47751675.950.363.21780
50875.649.662.71740
47750875.649.662.7661740
         
-46149575.148.861.91680
49174.948.561.71670
46149174.948.561.7651670
         
44447474.347.2611595
47274.247.160.81585
44447274.247.160.8631585
         
42942945573.445.759.7611510
41541544072.844.558.8591460
4014014257243.157.8581390
38838841071.441.856.8561330
37537539670.640.455.7541270
         
3633633837039.154.6521220
35235237269.3-11037.953.8511180
34134136068.7-10936.652.8501130
33133135068.1-108.535.551.9481095
32132133967.5-10834.351471060
         
31131132866.9-107.533.150461025
30230231966.3-10732.149.3451005
29329330965.7-10630.948.343970
28528530165.3-105.529.947.6950
27727729264.6-104.528.846.741925
         
26926928464.1-10427.645.940895
26226227663.6-10326.64539875
25525526963-10225.444.238850
24824826162.5-10124.243.237825
24124125361.810022.84236800
          
23523524761.49921.741.435785
22922924160.898.220.540.534765
22322323497.3-18.8 
21721722896.4-17.533725
21221222295.5-16705
         
20720721894.6-15.232690
20120121293.8-13.831675
19719720792.8-12.730655
19219220291.9-11.529640
18718719690.7-10620
         
18318319290-928615
17917918889-827600
17417418287.8-6.4585
17017017886.8-5.426570
16716717586-4.4560
         
16316317185-3.325545
15615616382.9-0.9525
14914915680.823505
14314315078.722490
13713714376.421460
         
13113113774450
1261261327220435
12112112769.819415
11611612267.618400
11111111765.715385

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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Shane
Author

Shane

Founder of MachineMFG

As the founder of MachineMFG, I have dedicated over a decade of my career to the metalworking industry. My extensive experience has allowed me to become an expert in the fields of sheet metal fabrication, machining, mechanical engineering, and machine tools for metals. I am constantly thinking, reading, and writing about these subjects, constantly striving to stay at the forefront of my field. Let my knowledge and expertise be an asset to your business.

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