Hardness Conversion Tables

Hardened Steel and Hard Alloys

C	A	D	Rockwell Scale				DPH 10 kg	KHN * 500 g and over	BHN 3000 kg	Tensile Strength, 103psi approximate
			15N	30N	45N	G
70	86.5	78.5	94.0	86.0	77.5	-	1076	972	-	-
69 68 67 66 65	86.0 85.5 85.0 84.5 84.0	78.0 77.0 76.0 75.5 74.5	93.5 - 93.0 92.5 92.0	85.0 84.5 83.5 83.0 82.0	76.5 75.5 74.5 73.0 72.0	- - - - -	1004 942 894 854 820	946 920 895 870 846	- - - - -	- - - - -
64 63 62 61 60	83.5 83.0 82.5 81.5 81.0	74.0 73.0 72.5 71.5 71.0	- 91.5 91.0 90.5 90.0	81.0 80.0 79.0 78.5 77.5	71.0 70.0 69.0 67.5 66.5	- - - - -	789 763 739 716 695	822 799 776 754 732	- - - - 614	- - - - -
59 58 57 56 55	80.5 80.0 79.5 79.0 78.5	70.0 69.0 68.5 67.5 67.0	89.5 - 89.0 88.5 88.0	76.5 75.5 75.0 74.0 73.0	65.5 64.0 63.0 62.0 61.0	- - - - -	675 655 636 617 598	710 690 670 650 630	600 587 573 560 547	- - - - 301
54 53 52 51 50	78.0 77.5 77.0 76.5 76.0	66.0 65.5 64.5 64.0 63.0	87.5 87.0 86.5 86.0 85.5	72.0 71.0 70.5 69.5 68.5	59.5 58.5 57.5 56.0 55.0	- - - - -	580 562 545 528 513	612 594 576 558 542	534 522 509 496 484	291 282 273 264 255
49 48 47 46 45	75.5 74.5 74.0 73.5 73.0	62.0 61.5 60.5 60.0 59.0	85.0 84.5 84.0 83.5 83.0	67.5 66.5 66.0 65.0 64.0	54.0 52.5 51.5 50.0 49.0	- - - - -	498 485 471 458 446	526 510 495 480 466	472 460 448 437 426	246 237 229 221 214
44 43 42 41 40	72.5 72.0 71.5 71.0 70.5	58.5 57.5 57.0 56.0 55.5	82.5 82.0 81.5 81.0 80.5	63.0 62.0 61.5 60.5 59.5	48.0 46.5 45.5 44.5 43.0	- - - - -	435 424 413 403 393	452 438 426 414 402	415 404 393 382 372	207 200 194 188 182
39 38 37 36 35	70.0 69.5 69.0 68.5 68.0	54.5 54.0 53.0 52.5 51.5	80.0 79.5 79.0 78.5 78.0	58.5 57.5 56.5 56.0 55.0	42.0 41.0 39.5 38.5 37.0	- - - - -	383 373 363 353 343	391 380 370 360 351	362 352 342 332 322	177 171 166 162 157
34 33 32 31 30	67.5 67.0 66.5 66.0 65.5	50.5 50 0 49.0 48.5 47.5	77.0 76.5 76.0 75.5 75.0	54.0 53.0 52.0 51.5 50.5	36.0 35.0 33.5 32.5 31.5	- - - - 92.0	334 325 317 309 301	342 334 326 318 311	313 305 297 290 283	153 148 144 140 136
29 28 27 26 25	65.0 64.5 64.0 63.5 63.0	47.0 46.0 45.5 44.5 44.0	74.5 74.0 73.5 72.5 72.0	49.5 48.5 47.5 47.0 46.0	30.0 29.0 28.0 26.5 25.5	91.0 90.0 89.0 88.0 87.0	293 285 278 271 264	304 297 290 284 278	276 270 265 260 255	132 129 126 123 120
24 23 22 21 20	62.5 62.0 61.5 61.0 60.5	43.0 42.5 41.5 41.0 40.0	71.5 71.0 70.5 70.0 69.5	45.0 44.0 43.0 42.5 41.5	24.0 23.0 22.0 20.5 19.5	86.0 84.5 83.5 82.5 81.0	257 251 246 241 236	272 266 261 256 251	250 245 240 235 230	117 115 112 110 108
* Knoop Hardness Conversion -- The values of the Knoop hardness number are approximate only. since they were determined on a limited number of tests and samples. These values are only for loads of 500 g or heavier. NOTE: Although conversion tables dealing with hardness can only be approximate and never mathmatically exact. it is of considerable value to be able to compare different hardness scales in a general way. Source: "Hardness Testing Handbook," by Vincent E. Lysaght and Anthony DeBellis, American Chain & Cable Co. and "Heat Treating Data Book," 7th Ed.. by Seco/Warwick Corp., Meadville, PA. 1986.

Receive news updates, technical information and more via email!