Common Hardness Comparison Table | Most Complete Collection

HV, HB, and HRC are all measurements of hardness used in materials testing. Let’s break them down:

1)HV Hardness (Vickers Hardness): HV hardness is a measure of a material’s resistance to indentation. It is determined by applying a known load to the surface of the material using a diamond indenter and measuring the size of the resulting indentation. HV hardness is expressed in units of Vickers hardness (HV) and is commonly used for thin materials, coatings, and small parts.

2)HB Hardness (Brinell Hardness): HB hardness is another measure of a material’s resistance to indentation. It involves applying a known load to the material using a hardened steel ball indenter and measuring the diameter of the resulting indentation. HB hardness is expressed in units of Brinell hardness (HB) and is often used for larger and bulkier materials, including metals and alloys.

3)HRC Hardness (Rockwell Hardness): HRC hardness is a measure of a material’s resistance to indentation or penetration. It uses different scales (A, B, C, etc.) based on the specific testing method and the type of indenter used (diamond cone or hardened steel ball). The HRC scale is commonly used for measuring the hardness of metallic materials. The hardness value is represented as a number on the HRC scale, such as HRC 50.

 

Commonly used HV-HB-HRC hardness comparison table:

Common ferrous metal hardness comparison table (approximate strength conversion)
Hardness classification

Tensile strength

N/mm2

Rockwell Vickers Brinell
HRC HRA HV HB
17 211 211 710
17.5 214 214 715
18 216 216 725
18.5 218 218 730
19 221 220 735
19.5 223 222 745
20 226 225 750
20.5 229 227 760
21 231 229 765
21.5 234 232 775
22 237 234 785
22.5 240 237 790
23 243 240 800
23.5 246 242 810
24 249 245 820
24.5 252 248 830
25 255 251 835
25.5 258 254 850
26 261 257 860
26.5 264 260 870
27 268 263 880
27.5 271 266 890
28 274 269 900
28.5 278 273 910
29 281 276 920
29.5 285 280 935
30 289 283 950
30.5 292 287 960
31 296 291 970
31.5 300 294 980
32 304 298 995
32.5 308 302 1010
33 312 306 1020
33.5 316 310 1035
34 320 314 1050
34.5 324 318 1065
35 329 323 1080
35.5 333 327 1095
36 338 332 1110
36.5 342 336 1125
37 347 341 1140
37.5 352 345 1160
38 357 350 1175
38.5 362 355 1190
39 70 367 360 1210
39.5 70.3 372 365 1225
40 70.8 382 375 1260
40.5 70.5 377 370 1245
41 71.1 388 380 1280
41.5 71.3 393 385 1300
42 71.6 399 391 1320
42.5 71.8 405 396 1340
43 72.1 411 401 1360
43.5 72.4 417 407 1385
44 72.6 423 413 1405
44.5 72.9 429 418 1430
45 73.2 436 424 1450
45.5 73.4 443 430 1475
46 73.7 449 436 1500
46.5 73.9 456 442 1525
47 74.2 463 449 1550
47.5 74.5 470 455 1575
48 74.7 478 461 1605
48.5 75 485 468 1630
49 75.3 493 474 1660
49.5 75.5 501 481 1690
50 75.8 509 488 1720
50.5 76.1 517 494 1750
51 76.3 525 501 1780
51.5 76.6 534 1815
52 76.9 543 1850
52.5 77.1 551 1885
53 77.4 561 1920
53.5 77.7 570 1955
54 77.9 579 1995
54.5 78.2 589 2035
55 78.5 599 2075
55.5 78.7 609 2115
56 79 620 2160
56.5 79.3 631 2205
57 79.5 642 2250
57.5 79.8 653 2295
58 80.1 664 2345
58.5 80.3 676 2395
59 80.6 688 2450
59.5 80.9 700 2500
60 81.2 713 2555
60.5 81.4 726
61 81.7 739
61.5 82 752
62 82.2 766
62.5 82.5 780
63 82.8 795
63.5 83.1 810
64 83.3 825
64.5 83.6 840
65 83.9 856
65.5 84.1 872
66 84.4 889
66.5 84.7 906
67 85 923
67.5 85.2 941
68 85.5 959
68.5 85.8 978
69 86.1 997
69.5 86.3 1017
70 86.6 1037

HRC/HB Approximate Conversion Tips

The hardness is higher than 20HRC, 1HRC≈10HB,
The hardness is lower than 20HRC, 1HRC≈11.5HB.
Remarks: For cutting processing, it can basically be converted uniformly 1HRC≈10HB (the hardness of the workpiece material has a fluctuation range)

 

Hardness of metal material

Hardness refers to the ability of a material to resist local deformation, especially plastic deformation, indentation or scratching. It is an index to measure the softness and hardness of the material.

According to different test methods, hardness is divided into three types.
Scratch hardness. It is mainly used to compare the softness and hardness of different minerals. The method is to choose a rod with one end hard and the other end soft, pass the material to be tested along the rod, and determine the hardness of the material to be tested according to the position of the scratch. Qualitatively speaking, hard objects make long scratches and soft objects make short scratches.

Indentation hardness. Mainly used for metal materials, the method is to use a certain load to press the specified indenter into the material to be tested, and compare the softness and hardness of the material to be tested by the size of the local plastic deformation on the surface of the material. Due to the difference of indenter, load and load duration, there are many kinds of indentation hardness, mainly including Brinell hardness, Rockwell hardness, Vickers hardness and microhardness.

Rebound hardness. Mainly used for metal materials, the method is to make a special small hammer fall freely from a certain height to impact the sample of the material to be tested, and use the amount of strain energy stored (and then released) in the sample during the impact (through the return of the small hammer) jump height measurement) to determine the hardness of the material.

    The most common Brinell hardness, Rockwell hardness and Vickers hardness of metal materials belong to the indentation hardness. The hardness value indicates the ability of the material surface to resist the plastic deformation caused by another object being pressed in; C) to measure the hardness, and the hardness value represents the size of the elastic deformation function of the metal.

Brinell Hardness

    Use a quenched steel ball or hard alloy ball with a diameter of D as the indenter, press it into the surface of the test piece with the corresponding test force F, and after a specified holding time, remove the test force to obtain an indentation with a diameter of d. Divide the test force by the surface area of the indentation, and the resulting value is the Brinell hardness value, and the symbol is represented by HBS or HBW.

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    The difference between HBS and HBW is the difference in the indenter. HBS means that the indenter is a hardened steel ball, which is used to measure materials with a Brinell hardness value below 450, such as mild steel, gray cast iron and non-ferrous metals. HBW means that the indenter is cemented carbide, which is used to measure materials with a Brinell hardness value below 650.

    For the same test block, when the other test conditions are exactly the same, the results of the two tests are different, and the HBW value is often greater than the HBS value, and there is no quantitative rule to follow.

    After 2003, my country has equivalently adopted international standards, canceled steel ball indenters, and all used carbide ball heads. Therefore, HBS is discontinued, and HBW is used to represent the Brinell hardness symbol. In many cases, the Brinell hardness is only expressed in HB, referring to HBW. However, HBS is still seen from time to time in literature papers.

    The Brinell hardness measurement method is suitable for cast iron, non-ferrous alloys, various annealed and quenched and tempered steels, and is not suitable for testing samples or cnc turning parts that are too hard, too small, too thin, or that do not allow large indentations on the surface.

Rockwell Hardness

    Use a diamond cone with a cone angle of 120° or Ø1.588mm and Ø3.176mm quenched steel balls as the indenter and the load to cooperate with it. The initial load is 10kgf and the total load is 60, 100 or 150kgf (that is, the initial load plus the main load). The hardness is expressed by the difference between the indentation depth when the main load is removed and the indentation depth when the main load is retained and the indentation depth under the initial load after the total load is applied.

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    The Rockwell hardness test uses three test forces and three indenters. There are 9 combinations of them, corresponding to the 9 scales of Rockwell hardness. The application of these 9 rulers covers almost all commonly used metal materials. There are three commonly used HRA, HRB and HRC, among which HRC is the most widely used.

Commonly used Rockwell hardness test specification table:

Hardness
symbol

Head type
Total test force
 F/N(kgf)

Hardness
scope

Application examples
HRA
120°
diamond cone
588.4(60)
20~88

Carbide, carbide,
Shallow case hardened steel etc.

HRB
Ø1.588mm
Quenched steel ball
980.7(100)
20~100

Annealed, normalized steel, aluminum alloy
Gold, copper alloy, cast iron

HRC
120°
diamond cone
1471(150)
20~70

hardened steel, quenched and tempered steel, deep
layer case hardened steel

 

    The range of use of the HRC scale is 20~70HRC. When the hardness value is less than 20HRC, because the conical aluminum cnc machining part of the indenter is pressed too much, the sensitivity decreases, and the HRB scale should be used instead; when the hardness of the sample is greater than 67HRC, the pressure on the tip of the indenter is too large, and the diamond is easily damaged. The life of the indenter will be greatly shortened, so the HRA scale should generally be used instead.

    The Rockwell hardness test is simple, rapid, and small indentation, and can test the surface of finished products and hard and thin workpieces. Due to the small indentation, for materials with uneven structure and hardness, the hardness value fluctuates greatly, and the accuracy is not as high as Brinell hardness. Rockwell hardness is used to determine the hardness of steel, non-ferrous metals, hard alloys, etc.

Vickers Hardness Vickers Hardness
    The principle of Vickers hardness measurement is similar to that of Brinell hardness. Use a diamond square pyramid indenter with an included angle of 136° to press into the surface of the material with a specified test force F, and remove the test force after maintaining the specified time. The hardness is expressed by the average pressure on the unit surface area of the square pyramid indentation. Value, the mark symbol is HV.

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    The Vickers hardness measurement range is large, and it can measure materials with a hardness ranging from 10 to 1000HV. The indentation is small, and it is generally used to measure thinner materials and surface hardened layers such as carburizing and nitriding.

Leeb Hardness Leeb Hardness
    Use an impact body with a certain mass of tungsten carbide ball head to impact the surface of the test piece under the action of a certain force, and then rebound. Due to the different hardness of materials, the rebound speed after impact is also different. A permanent magnet is installed on the impact device. When the impact body moves up and down, its peripheral coil will induce an electromagnetic signal proportional to the speed, and then convert it into a Leeb hardness value through an electronic circuit. The symbol is marked as HL.

    The Leeb hardness tester does not need a worktable, and its hardness sensor is as small as a pen, which can be directly operated by hand, and can be easily detected whether it is a large, heavy workpiece or a workpiece with complex geometric dimensions.

    Another advantage of Leeb hardness is that it has very little damage to the surface of the product, and sometimes it can be used as a non-destructive test; it is unique in hardness tests in all directions, narrow spaces and special aluminum parts.

 

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Post time: May-18-2023
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