Steel hardness test method and conversion table

Steel hardness describes the properties of steels that resist deformation, indentation, penetration, and scratching. steel hardness is important because the inherent resistance of the surface to withstand friction or erosion by oil, steam, and water from injection molding process,there are several harness test method as below:

steel hardness test

1.Brinell Hardness (HB)
Press a hardened steel ball of a certain size (usually 10mm in diameter) against the surface of the material with a certain load (usually 3,000kg) for a period of time. After the load is removed, the ratio of the load to the area of indentation is referred to as the Brinell hardness (HB), measured in kg/mm2 (N/mm2).

 

2.Vickers Hardness (HV)
Use a diamond square cone presser to penetrate into the surface of the material with a load of 120kg or less, and an apex angle of 136°. Then, divide the area of indentation in the material by the load, and we get the Vickers hardness (HV) value (kgf/mm2).

 

3.Rockwell Hardness (HR)
When HB>450 or the sample is too small, making it impossible to apply the Brinell hardness, the Rockwell hardness measurement will take the place. A diamond cone with an apex angle of 120° or a steel ball with a diameter of 1.59-3.18mm is pressed into the surface of the material to be tested under a certain load, and the hardness of the steels is determined based on the depth of the indentation. According to the hardness of the test material, it is measured by three different scales:

 

The Rockwell Hardness is comprised of three different standards, i.e., HRA, HRB and HRC, referred to A scale, B scale, and C scale.

HRA: The hardness obtained by using a 60kg load and a diamond cone indenter, applicable for materials with an extremely high hardness (such as cemented carbide).

 

HRB: The hardness obtained by using a load of 100kg and a hardened steel ball with the diameter of 1.58mm, applicable for materials with a lower hardness (such as annealed steel, and cast iron, etc.)

 

HRC: The hardness obtained by using a 150kg load and a diamond cone indenter, applicable for materials with a very high hardness (such as hardened steel).

Steel hardness conversion table

There are so many different types of steel hardness tests, a conversion table, such as the one below, allows us to take one measure and estimate the relative hardness on another measurement scale.

 

RmN/mm2 HV HB HRC RmN/mm2 HV HB HRC
250 80 76 1030 320 304 32.2
270 85 80.7 1060 330 314 33.3
285 90 85.2 1095 340 323 34.4
305 95 90.2 1125 350 333 35.5
320 100 95 1115 360 342 36.6
335 105 99.8 1190 370 352 37.7
350 110 105 1220 380 361 38.8
370 115 109 1255 390 371 39.8
380 120 114 1290 400 380 40.8
400 125 119 1320 410 390 41.8
415 130 124 1350 420 399 42.7
430 135 128 1385 430 409 43.6
450 140 133 1420 440 418 44.5
465 145 138 1455 450 428 45.3
480 150 143 1485 460 437 46.1
490 155 147 1520 470 447 46.9
510 160 152 1555 480 456 47.7
530 165 156 1595 490 466 48.4
545 170 162 1630 500 475 49.1
560 175 166 1665 510 485 49.8
575 180 171 1700 520 494 50.5
595 185 176 1740 530 504 51.1
610 190 181 1775 540 513 51.7
625 195 185 1810 550 523 52.3
640 200 190 1845 560 532 53
660 205 195 1880 570 542 53.6
675 210 199 1920 580 551 54.1
690 215 204 1955 590 561 54.7
705 220 209 1995 600 570 55.2
720 225 214 2030 610 580 55.7
740 230 219 2070 620 589 56.3
755 235 223 2105 630 599 56.8
770 240 228 20.3 2145 640 608 57.3
785 245 233 21.3 2180 650 618 57.8
800 250 238 22.2 660 58.3
820 255 242 23.1 670 58.8
835 260 247 24 680 59.2
850 265 252 24.8 690 59.7
865 270 257 25.6 700 60.1
880 275 261 26.4 720 61
900 280 266 27.1 740 61.8
915 285 271 27.8 760 62.5
930 290 276 28.5 780 63.3
950 295 280 29.2 800 64
965 300 285 29.8 820 64.7
995 310 295 31 840 65.3
860 65.9
880 66.4
900 67
920 67.5
940 68

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