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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 crucial performance index used to measure the resistance of materials to indentation or deformation caused by hard objects. This property is essential in various industrial applications, including material selection, quality control, and mechanical engineering.

Methods of Hardness Testing

Hardness testing methods vary, each with unique principles and implications behind the measured values. The primary categories of hardness tests include static load indentation tests and rebound hardness tests.

Static Load Indentation Hardness Tests

  1. Brinell Hardness (HB):
    • Commonly used for soft materials such as nonferrous metals, and steel before heat treatment.
    • A hardened steel ball or cemented carbide ball with a specific diameter is pressed into the material’s surface under a specified load. The hardness value is calculated by dividing the load by the indentation surface area.
  2. Rockwell Hardness (HR):
    • Suitable for materials with high surface hardness, such as those treated with heat.
    • Uses different scales based on the indenter and load:
      • HRA: Diamond cone, 60 kg load, for extremely hard materials.
      • HRB: 1.59 mm diameter steel ball, 100 kg load, for softer materials.
      • HRC: Diamond cone, 150 kg load, for harder materials.
    • The hardness value is determined by the depth of the indentation.
  3. Vickers Hardness (HV):
    • Suitable for microscopic analysis.
    • Uses a diamond square cone indenter with a top angle of 136°, pressed into the material under a load of less than 120 kg.
    • The hardness value is obtained by dividing the load by the surface area of the indentation pit.
  4. Shore Hardness (HA, HD):
    • Primarily used for rubber and plastics.

Rebound Hardness Tests

  1. Leeb Hardness (HL):
    • Measures the elastic deformation work of metals.
    • Involves bouncing an impact ball head on the material surface and calculating the hardness from the rebound speed relative to the impact speed.
  2. Shore Hardness (HS):
    • Used for various materials, measured by the indentation hardness of elastomers and rubbers.

Significance of Hardness

Hardness is not a single physical quantity but a comprehensive performance index that reflects a material’s elasticity, plasticity, strength, and toughness. It is crucial in understanding a material’s wear resistance, durability, and suitability for specific applications.

Hardness of steel

The hardness of metals, particularly steel, is denoted by the code H. Various hardness testing methods provide a detailed understanding of steel’s properties:

● 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)
––94085.6–6876.997–
––92085.3–67.576.596–
––90085–6776.195–
–-76788084.7–66.475.793–
–-75786084.4–65.975.392–
         
–-74584084.1–65.374.891–
–-73382083.8–64.774.390–
–-72280083.4–6473.888–
–-712–––––––
–-71078083–63.373.387–
–-69876082.6–62.572.686–
         
–-68474082.2–61.872.1––
–-68273782.2–61.77284–
–-67072081.8–6171.583–
–-65670081.3–60.170.8––
–-65369781.2–6070.781–
         
–-64769081.1–59.770.5––
–-63868080.8–59.270.180–
–63067080.6–58.869.8––
–62766780.5–58.769.779–
         
––67780.7–59.170––
–60164079.8–57.368.777–
         
––64079.8–57.368.7––
–57861579.1–5667.775–
         
––60778.8–55.667.4––
–55559178.4–54.766.7732055
         
––57978–5466.1–2015
–53456977.8–53.565.8711985
         
––53377.1–52.565–1915
–51454776.9–52.164.7701890
         
-495–53976.7–51.664.3–1855
––53076.4–51.163.9–1825
–49552876.3–5163.8681820
         
-477–51675.9–50.363.2–1780
––50875.6–49.662.7–1740
–47750875.6–49.662.7661740
         
-461–49575.1–48.861.9–1680
––49174.9–48.561.7–1670
–46149174.9–48.561.7651670
         
444–47474.3–47.261–1595
––47274.2–47.160.8–1585
–44447274.2–47.160.8631585
         
42942945573.4–45.759.7611510
41541544072.8–44.558.8591460
40140142572–43.157.8581390
38838841071.4–41.856.8561330
37537539670.6–40.455.7541270
         
36336338370–39.154.6521220
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
28528530165.3-105.529.947.6–950
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
223223234–97.3-18.8–– 
217217228–96.4-17.5–33725
212212222–95.5-16––705
         
207207218–94.6-15.2–32690
201201212–93.8-13.8–31675
197197207–92.8-12.7–30655
192192202–91.9-11.5–29640
187187196–90.7-10––620
         
183183192–90-9–28615
179179188–89-8–27600
174174182–87.8-6.4––585
170170178–86.8-5.4–26570
167167175–86-4.4––560
         
163163171–85-3.3–25545
156156163–82.9-0.9––525
149149156–80.8––23505
143143150–78.7––22490
137137143–76.4––21460
         
131131137–74–––450
126126132–72––20435
121121127–69.8––19415
116116122–67.6––18400
111111117–65.7––15385

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　　　

Tables are essential for converting hardness values between different scales and understanding the relationship between hardness and other mechanical properties, such as tensile strength.

Conclusion

Hardness testing is an essential method in material science and engineering to determine a material’s suitability for specific applications. By understanding the different methods and their appropriate uses, one can select the best testing technique to ensure material performance and reliability. This comprehensive guide aims to provide a deeper insight into hardness testing, enabling better material selection and quality control in various industries.

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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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