Metal Hardness: The Definite Guide (with Hardness Chart)

What is metal hardness?

Hardness refers to the ability of a material to resist local deformation, especially plastic deformation, indentations or scratches.

It is an indicator of the hardness of the material.

Types of metal hardness

According to the different test methods, there are three types of hardness.

① Scratch hardness

It is mainly used to compare the hardness of different minerals.

The method is to choose a stick with a hard end and a soft end, and slide the material to be tested along the rod, and determine the softness and hardness of the material to be tested according to the location of the scratch.

Qualitatively speaking, the scratches made by hard objects are long and the scratches made by soft objects are short.

② Indentation hardness

Mainly used for metal materials, the method is to press the specified indenter into the material under test with a certain load, and compare the softness and hardness of the material under test with the local plastic deformation of the material surface.

Due to different indenters, loads, and load durations, there are a variety of indentation hardness, mainly Brinell hardness, Rockwell hardness, Vickers hardness, and micro-hardness.

③ Rebound hardness

Mainly used for metal materials.

The method is to make a special small hammer drop freely from a certain height to impact the sample of the tested material, and the hardness of the material is determined by the amount of strain energy (measured by the rebound height of the hammer) stored in (and then release) the sample during the impact.

Non-ferrous Metal Hardness Table

Non-ferrous Metal Hardness Tensile strength δb/MPa
Rockwell Surface Rockwell Vickers Brinell(F/D2=30) 
HRC HRA HR15N HR30N HR45N HV HBS HBW MS Cr.S Cr-V.S CrNi.S Cr-Mo.S Cr-Ni-Mo .S CrMnSi.S UHSS S.S
20.0 60.2 68.8 40.7 19.2 226 225 225 774 742 736 782 747 / 781 / 740
20.5 60.4 69.0 41.2 19.8 228 227 227 784 751 744 787 753 / 788 / 749
21.0 60.7 69.3 41.7 20.4 230 229 229 793 760 753 792 760 / 794 / 758
21.5 61.0 69.5 42.2 21.0 233 232 232 803 769 761 797 767 / 801 / 767
22.0 61.2 69.8 42.6 21.5 235 234 234 813 779 770 803 774 / 809 / 777
22.5 61.5 70.0 43.1 22.1 238 237 237 823 788 779 809 781 / 816 / 786
23.0 61.7 70.3 43.6 22.7 24l 240 240 833 798 788 815 789 / 824 / 796
23.5 62.0 70.6 44.0 23.3 244 242 242 843 808 797 822 797 / 832 / 806
24.0 62.2 70.8 44.5 23.9 247 245 245 854 818 807 829 805 / 840 / 816
24.5 62.5 71.1 45.0 24.5 250 248 248 864 828 816 836 813 / 848 / 826
25.0 62.8 71.4 45.5 25.1 253 251 251 875 838 826 843 822 / 856 / 837
25.5 63.0 71.6 45.9 25.7 256 254 254 886 848 837 851 831 850 865 / 847
26.0 63.3 71.9 46.4 26.3 259 257 257 897 859 847 859 840 859 874 / 858
26.5 63.5 72.2 46.9 26.9 262 260 260 908 870 858 867 850 869 883 / 868
27.0 63.8 72.4 47.3 27.5 266 263 263 919 880 869 876 860 879 893 / 879
27.5 64.0 72.7 47.8 28.1 269 266 266 930 891 880 885 870 890 902 / 890
28.0 64.3 73.0 48.3 28.7 273 269 269 942 902 892 894 880 901 912 / 901
28.5 64.6 73.3 48.7 29.3 276 273 273 954 914 903 904 891 912 922 / 913
29.0 64.8 73.5 49.2 29.9 280 276 276 965 925 915 914 902 923 933 / 924
29.5 65.1 73.8 49.7 30.5 284 280 280 977 937 928 924 913 935 943 / 936
30.0 65.3 74.1 50.2 31.1 288 283 283 989 948 940 935 924 947 954 / 947
30.5 65.6 74.4 50.6 31.7 292 287 287 1002 960 953 946 936 959 965 / 959
31.0 65.8 74.7 51.1 32.3 296 29l 29l 1014 972 966 957 948 972 977 / 971
31.5 66.1 74.9 51.6 32.9 300 294 294 1027 984 980 969 961 985 989 / 983
32.0 66.4 75.2 52.0 33.5 304 298 298 1039 996 993 981 974 999 1001 / 996
32.5 66.6 75.5 52.5 34.1 308 302 302 1052 1009 1007 994 987 1012 1013 / 1008
33.0 66.9 75.8 53.0 34.7 313 306 306 1065 1022 1022 1007 1001 1027 1026 / 1021
33.5 67.1 76.1 53.4 35.3 317 310 310 1078 1034 1036 1020 1015 1041 1039 / 1034
34.0 67.4 76.4 53.9 35.9 32l 314 314 1092 1048 1051 1034 1029 1056 1052 / 1047
34.5 67.7 76.7 54.4 36.5 326 318 318 1105 1061 1067 1048 1043 1071 1066 / 1060
35.0 67.9 77.0 54.8 37.0 33l 323 323 1119 1074 1082 1063 1058 1087 1079 / 1074
35.5 68.2 77.2 55.3 37.6 335 327 327 1133 1088 1098 1078 1074 1103 1094 / 1087
36.0 68.4 77.5 55.8 38.2 340 332 332 1147 1102 1114 1093 1090 1119 1108 / 1101
36.5 68.7 77.8 56.2 38.8 345 336 336 1162 1116 1131 1109 1106 1136 1123 / 1116
37.0 69.0 78.1 56.7 39.4 350 341 341 1177 1131 1148 1125 1122 1153 1139 / 1130
37.5 69.2 78.4 57.2 40.0 355 345 345 1192 1146 1165 1142 1139 1171 1155 / 1145
38.0 69.5 78.7 57.6 40.6 360 350 350 1207 1161 1183 1159 1157 1189 1171 / 1161
38.5 69.7 79.0 58.1 41.2 365 355 355 1222 1176 1201 1177 1174 1207 1187 1170 1176
39.0 70.0 79.3 58.6 41.8 37l 360 360 1238 1192 1219 1195 1192 1226 1204 1195 1193
39.5 70.3 79.6 59.0 42.4 376 365 365 1254 1208 1238 1214 1211 1245 1222 1219 1209
40.0 70.5 79.9 59.5 43.0 381 370 370 1271 1225 1257 1233 1230 1265 1240 1243 1226
40.5 70.8 80.2 60.0 43.6 387 375 375 1288 1242 1276 1252 1249 1285 1258 1267 1244
41.0 71.1 80.5 60.4 44.2 393 380 381 1305 1260 1296 1273 1269 1306 1277 1290 1262
41.5 71.3 80.8 60.9 44.8 398 385 386 1322 1278 1317 1293 1289 1327 1296 1313 1280
42.0 71.6 81.1 61.3 45.4 404 39l 392 1340 1296 1337 1314 1310 1348 1316 1336 1299
42.5 71.8 81.4 61.8 45.9 410 396 397 1359 1315 1358 1336 1331 1370 1336 1359 1319
43.0 72.1 81.7 62.3 46.5 416 40l 403 1378 1335 1380 1358 1353 1392 1357 1381 1339
43.5 72.4 82.0 62.7 47.1 422 407 409 1397 1355 1401 1380 1375 1415 1378 1404 1361
44.0 72.6 82.3 63.2 47.7 428 413 415 1417 1376 1424 1404 1397 1439 1400 1427 1383
44.5 72.9 82.6 63.6 48.3 435 418 422 1438 1398 1446 1427 1420 1462 1422 1450 1405
45.0 73.2 82.9 64.1 48.9 44l 424 428 1459 1420 1469 1451 1444 1487 1445 1473 1429
45.5 73.4 83.2 64.6 49.5 448 430 435 1481 1444 1493 1476 1468 1512 1469 1496 1453
46.0 73.7 83.5 65.0 50.1 454 436 44l 1503 1468 1517 1502 1492 1537 1493 1520 1479
46.5 73.9 83.7 65.5 50.7 46l 442 448 1526 1493 1541 1527 1517 1563 1517 1544 1505
47.0 74.2 84.0 65.9 51.2 468 449 455 1550 1519 1566 1554 1542 1589 1543 1569 1533
47.5 74.5 84.3 66.4 51.8 475 / 463 1575 1546 1591 1581 1568 1616 1569 1594 1562
48.0 74.7 84.6 66.8 52.4 482 / 470 1600 1574 1617 1608 1595 1643 1595 1620 1592
48.5 75.0 84.9 67.3 53.0 489 / 478 1626 1603 1643 1636 1622 1671 1623 1646 1623
49.0 75.3 85.2 67.7 53.6 497 / 486 1653 1633 1670 1665 1649 1699 1651 1674 1655
49.5 75.5 85.5 68.2 54.2 504 / 494 1681 1665 1697 1695 1677 1728 1679 1702 1689
50.0 75.8 85.7 68.6 54.7 512 502 502 1710 1698 1724 1724 1706 1758 1709 1731 1725
50.5 76.1 86.0 69.1 55.3 520 510 510 / 1732 1752 1755 1735 1788 1739 1761 /
51.0 76.3 86.3 69.5 55.9 527 518 518 / 1768 1780 1786 1764 1819 1770 1792 /
51.5 76.6 86.6 70.0 56.5 535 527 527 / 1806 1809 1818 1794 1850 1801 1824 /
52.0 76.9 86.8 70.4 57.1 544 535 535 / 1845 1839 1850 1825 1881 1834 1857 /
52.5 77.1 87.1 70.9 57.6 552 544 544 / / 1869 1883 1856 1914 1867 1892 /
53.0 77.4 87.4 71.3 58.2 561 552 552 / / 1899 1917 1888 1947 1901 1929 /
53.5 77.7 87.6 71.8 58.8 569 56l 56l / / 1930 1951 / / 1936 1966 /
54.0 77.9 87.9 72.2 59.4 578 569 569 / / 1961 1986 / / 1971 2006 /
54.5 78.2 88.1 72.6 59.9 587 577 577 / / 1993 2022 / / 2008 2047 /
55.0 78.5 88.4 73.1 60.5 596 585 585 / / 2026 2058 / / 2045 2090 /
55.5 78.7 88.6 73.5 61.1 606 593 593 / / / / / / / 2135 /
56.0 79.0 88.9 73.9 61.7 615 601 601 / / / / / / / 2181 /
56.5 79.3 89.1 74.4 62.2 625 608 608 / / / / / / / 2230 /
57.0 79.5 89.4 74.8 62.8 635 616 616 / / / / / / / 2281 /
57.5 79.8 89,6 75.2 63.4 645 622 622 / / / / / / / 2334 /
58.0 80.1 89.8 75.6 63.9 655 628 628 / / / / / / / 2390 /
58.5 80.3 90.0 76.1 64.5 666 634 634 / / / / / / / 2448 /
59.0 80.6 90.2 76.5 65.1 676 639 639 / / / / / / / 2509 /
59.5 80.9 90.4 76.9 65.6 687 643 643 / / / / / / / 2572 /
60.0 81.2 90.6 77.3 66.2 698 647 647 / / / / / / / / /
60.5 81.4 90.8 77.7 66.8 710 650 650 / / / / / / / / /
61.0 81.7 91.0 78.1 67.3 72l / / / / / / / / / / /
61.5 82.0 91.2 78.6 67.9 733 / / / / / / / / / / /
62.0 82.2 91.4 79.0 68.4 745 / / / / / / / / / / /
62.5 82.5 91.5 79.4 69.0 757 / / / / / / / / / / /
63.0 82.8 91.7 79.8 69.5 770 / / / / / / / / / / /
63.5 83.1 91.8 80.2 70.1 782 / / / / / / / / / / /
64.0 83.3 91.9 80.6 70.6 795 / / / / / / / / / / /
64.5 83.6 92.1 81.0 71.2 809 / / / / / / / / / / /
65.0 83.9 92.2 81.3 71.1 822 / / / / / / / / / / /
65.5 84.1 / / / 836 / / / / / / / / / / /
66.0 84.4 / / / 850 / / / / / / / / / / /
66.5 84.7 / / / 865 / / / / / / / / / / /
67.0 85.0 / / / 879 / / / / / / / / / / /
67.5 85.2 / / / 894 / / / / / / / / / / /
68.0 85.5 / / / 909 / / / / / / / / / / /

Ferrous Metal Hardness Table

The following data is mainly applicable to low-carbon steel (mild steel).

Ferrous Metal Hardness Tensile strength
Rockwell Surface Rockwell Vickers Brinell HBS
HRB HR15T HR30T HR45T HV F/D2=10 F/D2=10 MPa
60.0 80.4 56.1 30.4 105 102 / 375
60.5 80.5 56.4 30.9 105 102 / 377
61.0 80.7 56.7 31.4 106 103 / 379
61.5 80.8 57.1 31.9 107 103 / 381
62.0 80.9 57.4 32.4 108 104 / 382
62.5 81.1 57.7 32.9 108 104 / 384
63.0 81.2 58.0 33.5 109 105 / 386
63.5 81.4 58.3 34.0 110 105 / 388
64.0 81.5 58.7 34.5 110 106 / 390
64.5 81.6 59.0 35.0 11l 106 / 393
65.0 81.8 59.3 35.5 112 107 / 395
65.5 81.9 59.6 36.1 113 107 / 397
66.0 82.1 59.9 36.6 114 108 / 399
66.5 82.2 60.3 37.1 115 108 / 402
67.0 82.3 60.6 37.6 115 109 / 404
67.5 82.5 60.9 38.1 116 110 / 407
68.0 82.6 61.2 38.6 117 110 / 409
68.5 82.7 61.5 39.2 118 111 / 412
69.0 82.9 61.9 39.7 119 112 / 415
69.5 83.0 62.2 40.2 120 112 / 418
70.0 83.2 62.5 40.7 12l 113 / 42l
70.5 83.3 62.8 41.2 122 114 / 424
71.0 83.4 63.1 41.7 123 115 / 427
71.5 83.6 63.5 42.3 124 115 / 430
72.0 83.7 63.8 42.8 125 116 / 433
72.5 83.9 64.1 43.3 126 117 / 437
73.0 84.0 64.4 43.8 128 118 / 440
73.5 84.1 64.7 44.3 129 119 / 444
74.0 84.3 65.1 44.8 130 120 / 447
74.5 84.4 65.4 45.4 13l 12l / 451
75.0 84.5 65.7 45.9 132 122 152 455
75.5 84.7 66.0 46.4 134 123 155 459
76.0 84.8 66.3 46.9 135 124 156 463
76.5 85.0 66.6 47.4 136 125 158 467
77.0 85.1 67.0 47.9 138 126 159 471
77.5 85.2 67.3 48.5 139 127 16l 475
78.0 85.4 67.6 49.0 140 128 163 480
78.5 85.5 67.9 49.5 142 129 164 484
79.0 85.7 68.2 50.0 143 130 166 489
79.5 85.8 68.6 50.5 145 132 168 493
80.0 85.9 68.9 51.0 146 133 170 498
80.5 86.1 69.2 51.6 148 134 172 503
81.0 86.2 69.5 52.1 149 136 174 508
81.5 86.3 69.8 52.6 151 137 / 513
82.0 86.5 70.2 53.1 152 138 / 518
82.5 86.6 70.5 53.6 154 140 / 523
83.0 86.8 70.8 54.1 156 / / 529
83.5 86.9 71.1 54.7 157 / / 534
84.0 87.0 71.4 55.2 159 / / 540
84.5 87.2 71.8 55.7 16l / / 546
85.0 87.3 72.1 56.2 163 / / 551
85.5 87.5 72.4 56.7 165 / / 557
86.0 87.6 72.7 57.2 166 / / 563
86.5 87.7 73.0 57.8 168 / / 570
87.0 87.9 73.4 58.3 170 / / 576
87.5 88.0 73.7 58.8 172 / / 582
88.0 88.1 74.0 59.3 174 / / 589
88.5 88.3 74.3 59.8 176 / / 596
89.0 88.4 74.6 60.3 178 / / 603
89.5 88.6 75.0 60.9 180 / / 609
90.0 88.7 75.3 61.4 183 / 176 617
90.5 88.8 75.6 61.9 185 / 178 624
91.0 89.0 75.9 62.4 187 / 180 63l
91.5 89.1 76.2 62.9 189 / 182 639
92.0 89.3 76.6 63.4 191 / 184 646
92.5 89.4 76.9 64.0 194 / 187 654
93.0 89.5 77.2 64.5 196 / 189 662
93.5 89.7 77.5 65.0 199 / 192 670
94.0 89.8 77.8 65.5 201 / 195 678
94.5 89.9 78.2 66.0 203 / 197 686
95.5 90.1 78.5 66.5 206 / 200 695
95.0 90.2 78.8 67.1 208 / 203 703
96.0 90.4 79.1 67.6 211 / 206 712
96.5 90.5 79.4 68.1 214 / 209 721
97.0 90.6 79.8 68.6 216 / 212 730
97.5 90.8 80.1 69.1 219 / 215 739
98.0 90.9 80.4 69.6 222 / 218 749
98.5 91.1 80.7 70.2 225 / 222 758
99.0 91.2 81.0 70.7 227 / 226 768
99.5 91.3 81.4 71.2 230 / 229 778
100.0 91.5 81.7 71.7 233 / 232 788

Common HV = HB = HRC hardness comparison table

Hardness comparison table of common ferrous metals (Approximate conversion of intensity)

RockwellRockwellVickersBrinellTensile strength
HRCHRAHVHBN/mm2
17211211710
17.5214214715
18216216725
18.5218218730
19221220735
19.5223222745
20226225750
20.5229227760
21231229765
21.5234232775
22237234785
22.5240237790
23243240800
23.5246242810
24249245820
24.5252248830
25255251835
25.5258254850
26261257860
26.5264260870
27268263880
27.5271266890
28274269900
28.5278273910
29281276920
29.5285280935
30289283950
30.5292287960
31296291970
31.5300294980
32304298995
32.53083021010
333123061020
33.53163101035
343203141050
34.53243181065
353293231080
35.53333271095
363383321110
36.53423361125
373473411140
37.53523451160
383573501175
38.53623551190
39703673601210
39.570.33723651225
4070.83823751260
40.570.53773701245
4171.13883801280
41.571.33933851300
4271.63993911320
42.571.84053961340
4372.14114011360
43.572.44174071385
4472.64234131405
44.572.94294181430
4573.24364241450
45.573.44434301475
4673.74494361500
46.573.94564421525
4774.24634491550
47.574.54704551575
4874.74784611605
48.5754854681630
4975.34934741660
49.575.55014811690
5075.85094881720
50.576.15174941750
5176.35255011780
51.576.65341815
5276.95431850
52.577.15511885
5377.45611920
53.577.75701955
5477.95791995
54.578.25892035
5578.55992075
55.578.76092115
56796202160
56.579.36312205
5779.56422250
57.579.86532295
5880.16642345
58.580.36762395
5980.66882450
59.580.97002500
6081.27132555
60.581.4726
6181.7739
61.582752
6282.2766
62.582.5780
6382.8795
63.583.1810
6483.3825
64.583.6840
6583.9856
65.584.1872
6684.4889
66.584.7906
6785923
67.585.2941
6885.5959
68.585.8978
6986.1997
69.586.31017
7086.61037

Download Ferrous & Non-ferrous Metal Hardness Table

Metal hardness and strength conversion value, strength and hardness comparison table

HRC / HB approximate conversion tips

  • When the hardness is higher than 20HRC, 1HRC≈10HB,
  • When the hardness is lower than 20HRC, 1HRC≈11.5HB.

Notes: For cutting processing, 1HRC≈10HB can be basically converted (the hardness of the workpiece material has a fluctuation range)

The most common Brinell, Rockwell, and Vickers hardnesses of metal materials are all indentation hardness.

The hardness value indicates the ability of the surface of a material to resist plastic deformation caused by the intrusion of another object.

When measuring the hardness by the back-jumping method, the hardness value represents the size of the metal’s elastic deformation function.

Commonly used hardness

Brinell Hardness

A hardened steel ball or hard alloy ball with a diameter of D is used as the indenter, and the corresponding test force F is pressed into the surface of the test piece.

After the prescribed holding time, the test force is removed to obtain an indentation of diameter d. Divide the test force by the indentation surface area.

The value obtained is the Brinell hardness value, and the symbol is expressed by HBS or HBW.

Brinell Hardness

The difference between HBS and HBW is the indenter. 

HBS indicates that the indenter is a hardened steel ball, which is used to determine materials with a Brinell hardness value below 450, such as mild steel, gray cast iron and non-ferrous metals.

HBW indicates that the indenter is a hard alloy, which is used to measure materials with a Brinell hardness value below 650.

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

HBW Formula

After 2003, China has adopted international standards equivalently, eliminating steel ball indenters and using hard alloy ball heads.

Therefore, HBS was discontinued, and all Brinell hardness symbols were represented by HBW.

Many times Brinell hardness is only expressed by HB, which means HBW. However, HBS is still seen in the literature.

The Brinell hardness measurement method is suitable for cast iron, non-ferrous alloys, various annealed as well as quenched and tempered steels.

It is not suitable to measure samples or workpieces that are too hard, too small, too thin, and do not allow large indentations on the surface.

Rockwell Hardness

A diamond cone with a cone apex angle of 120 ° or Ø1.588mm and Ø3.176mm hardened steel ball is used as the indenter and used in conjunction with the load. Under the initial load of 10kgf and the total load (that is, the initial load plus main load) of 60, 100 or 150kgf force, press the sample.

After the total load, the hardness is expressed by the difference between the indentation depth when the main load is removed while the main load is retained and the indentation depth under the initial load.

Rockwell Hardness

The Rockwell hardness test uses three test forces and three indenters, which have a total of nine combinations, corresponding to nine 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, of which HRC is the most widely used.

Table of commonly used Rockwell hardness test specifications

Hardness symbolIndenter typeTotal test forceF/N(kgf)Hardness rangeApplications
HRA120°diamond cone588.4(60)20~88Hard alloy, carbide, shallow case hardening steel and etc.
HRBØ1.588mm Quenched steel ball980.7(100)20~100Annealed or normalized steel, aluminum alloy, copper alloy, cast iron
HRC120°diamond cone1471(150)20~70Hardened steel, quenched and tempered steel, deep case hardening steel

The use range of HRC scale is 20 ~ 70HRC. 

When the hardness value is less than 20HRC, because the conical part of the indenter is pressed too much, the sensitivity is reduced, 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, the diamond is easily damaged, and the life of the indenter will be greatly shortened.

Therefore, the HRA scale should be used instead.

The Rockwell hardness test is simple, fast, and has small indentation.

It can test the surface of finished products and harder and thinner work pieces. 

Because the indentation is small, the hardness value fluctuates greatly for materials with uneven structure and hardness, and the accuracy is not as high as the Brinell hardness.

Rockwell hardness is used to determine the hardness of steel, non-ferrous metals, cemented carbide, and the like.

Vickers Hardness

Vickers Hardness

The Vickers hardness measurement principle is similar to Brinell hardness.

A diamond quadrangular pyramid indenter with an opposite angle of 136 ° was used to press the surface of the material with a specified test force F.

The test force is removed after holding for a specified time, and the hardness value is expressed by the average pressure on the unit surface area of the regular quadrangular pyramid indentation, and the symbol is HV.

HV Formula

The Vickers hardness measurement range is large, and it can measure materials with a hardness in the range of 10 ~ 1000HV, and the indentation is small.

It is generally used to measure thin materials and surface hardened layers with carburizing and nitriding.

Leeb Hardness

A certain mass of impact body equipped with tungsten carbide ball head is used to impact the surface of the test piece under a certain force, and then rebound.

Due to different material hardness, the rebound speed after impact is also different. Permanent magnetic material 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.

Then it is converted into Leeb hardness value by the electronic circuit, and the symbol is HL.

The Leeb hardness tester does not require a workbench. Its hardness sensor is as small as a pen and can be directly operated by hand. 

Whether it is large, heavy or complex geometries, it can be easily inspected.

Another advantage of Leeb hardness is that the surface of the product is lightly damaged and sometimes used for a non-destructive test.

It has a unique hardness test in all directions, narrow space and special parts.

Hardness testers

  • Micro Vickers hardness testing machine

HM series:

Micro Vickers hardness testing machine

  • Vickers hardness testing machine
    HV series:
Vickers hardness testing machine

  • Rockwell hardness testing machine
    HR series:
Rockwell hardness testing machine

  • Portable Leeb hardness tester
    HH series:
Portable Leeb hardness tester

FAQs about metal hardness

How to measure hardness of metal?

Brinell hardness method, Rockwell hardness method and Vickers hardness method are the most commonly used methods to measure the hardness of metal.

How to increase metal hardness?

The strength of metal materials can be improved in the following five ways:

1) Carry out heat treatment process, and carry out heat treatment, quenching, tempering, normalizing, etc. according to the required performance and structure.

2) Shot peening on the surface can also improve the strength.

3) Grain boundary strengthening.

4) Dislocation strengthening.

5) Some compounds precipitated by deformation and aging can improve the strength.

At what temperature does metal lose hardness

At more than 200 degrees below zero, ordinary steel is as fragile as shrimps. Low temperature reduces the activity force between metal molecules and increases the rigidity of matter.

Simply put, the more it can not bear deformation, so it is easy to break under external force.

However, whether it will become brittle depends on the situation. For example, there is no low-temperature ductile brittle transition for face centered cubic materials.

What determines the hardness of a metal?

1). The hardness of metal depends on the strength of metal bond in metal;

2). The smaller the radius of metal atom, the stronger the metal bond and the greater the hardness;

3). The more valence electrons in the metal per unit volume, the stronger the metal bond and the greater the hardness.

Generally speaking, for the main group metals, from left to right, in the same period, the atomic radius decreases and the number of valence electrons increases, so the hardness increases;

4). From top to bottom, with the same main group, the atomic radius increases and the number of valence electrons is the same, so the hardness decreases;

5). For transition elements, the radius decreases from left to right, but the number of valence electrons first increases and then decreases.

Therefore, the law may not be as obvious as the main family.

However, elements with high hardness are generally in the middle of the transition elements with the same period.

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