Hardness conversion table: HLD, HRC, HRB, HV, HB, HSD

What is hardness?

Hardness refers to the ability of a material to resist the penetration of a hard object into its surface. It is one of the important performance indicators of metallic materials.

Generally, the higher the hardness, the better the wear resistance. Common hardness indicators include Brinell hardness, Rockwell hardness, and Vickers hardness.

1. Brinell Hardness (HB)

This is determined by applying a certain load (usually 3,000 kg) to a hardened steel ball of a certain size (usually 10 mm in diameter) pressed into the surface of the material, held for a period, and after unloading, the relationship between the load and its indentation area is the Brinell hardness value (HB), the unit is KN/mm ² (N/mm ² ).

2. Rockwell Hardness (HR)

When HB>450 or the sample is too small, Brinell hardness test cannot be used and Rockwell hardness measurement is adopted. It is determined by pressing a diamond cone with a top angle of 120° or a steel ball with a diameter of 1.59,3.18 mm on the surface of the material under a certain load, and the hardness of the material is calculated from the depth of retreat. According to the different hardness of the testing material, it is expressed in three different scales:

• HRA: Hardness obtained using a 60kg load and conical diamond indenter, used for extremely hard materials (such as hard alloys).
• HRB: Hardness obtained using a load of 100kg and a tempered steel ball with a diameter of 1.58mm, used for materials of lower hardness (such as annealed steel, cast iron).
• HRC: Hardness obtained with a load of 150kg and conical diamond indenter, used for very hard materials (such as tempered steel).

3. Vickers Hardness (HV)

By pressing a square diamond cone with a top angle of 136° and a load of 120 kg or less onto the surface of the material, the HV value of the Vickers hardness (kgf/mm ² ) is obtained by dividing the surface area of ​​the indentation pit of the material for the value of the load.

4. HLD (Leeb hardness):

Leeb hardness is a metric used to measure the local or general hardness of metallic materials. It is determined by measuring the material's response to impact load. The Leeb hardness value can be converted to other hardness units such as Rockwell hardness and Brinell hardness.

5. HSD (Shore hardness):

Shore hardness is a method for measuring the hardness of non-metallic materials. It is determined by measuring the resistance of the material to a specific shape of indenter. Shore hardness values ​​can also be converted to other hardness units.

Observation:

In Rockwell hardness, HRA, HRB and HRC are three different standards, called Scale A, Scale B and Scale C.

The Rockwell hardness test is one of several common indentation hardness tests used today. All three scales start with an initial pressure of 98.07N (equivalent to 10kgf), and the hardness value is calculated based on the depth of indentation. Scale A uses a conical diamond indenter and applies pressure of up to 588.4N (equivalent to 60kgf); Scale B uses a steel ball with a diameter of 1.588mm (1/16 inch) as a penetrator and applies pressure of up to 980.7N (equivalent to 100kgf); Scale C uses the same diamond cone as Scale A, but the pressure applied is 1471N (equivalent to 150kgf). Therefore, Scale B is suitable for relatively softer materials, while Scale C is suitable for harder materials.

Experience has shown that there is an approximate correlation between various hardness values ​​of metallic materials and between hardness values ​​and strength values. Since the hardness value is determined by the resistance to initial plastic deformation and the subsequent resistance to plastic deformation, the greater the strength of the material, the greater the resistance to plastic deformation and therefore the greater the hardness value. However, the conversion relationship of various materials is not consistent.

See the “Hardness Comparison Table” on this website, which provides a table for converting different steel hardness values.

Hardness Conversion Table

According to German standard DIN50150, below is the tensile strength comparison table of commonly used steel materials with Vickers hardness, Brinell hardness and Rockwell hardness.

1. HB, HB, HRC hardness table

Tensile strength Rm (N/ mm2 )	Vickers hardness High voltage	Brinell hardness HB	Rockwell hardness CDH
250	80	76.0	–
270	85	80.7	–
285	90	85.2	–
305	95	90.2	–
320	100	95.0	–
335	105	99.8	–
350	110	105	–
370	115	109	–
380	120	114	–
400	125	119	–
415	130	124	–
430	135	128	–
450	140	133	–
465	145	138	–
480	150	143	–
490	155	147	–
510	160	152	–
530	165	156	–
545	170	162	–
560	175	166	–
575	180	171	–
595	185	176	–
610	190	181	–
625	195	185	–
640	200	190	–
660	205	195	–
675	210	199	–
690	215	204	–
705	220	209	–
720	225	214	–
740	230	219	–
755	235	223	–
770	240	228	20.3
785	245	233	21.3
800	250	238	22.2
820	255	242	23.1
835	260	247	24.0
850	265	252	24.8
865	270	257	25.6
880	275	261	26.4
900	280	266	27.1
915	285	271	27.8
930	290	276	28.5
950	295	280	29.2
965	300	285	29.8
995	310	295	31.0
1030	320	304	32.2
1060	330	314	33.3
1095	340	323	34.4
1125	350	333	35.5
1115	360	342	36.6
1190	370	352	37.7
1220	380	361	38.8
1255	390	371	39.8
1290	400	380	40.8
1320	410	390	41.8
1350	420	399	42.7
1385	430	409	43.6
1420	440	418	44.5
1455	450	428	45.3
1485	460	437	46.1
1520	470	447	46.9
1555	480	(456)	47.7
1595	490	(466)	48.4
1630	500	(475)	49.1
1665	510	(485)	49.8
1700	520	(494)	50.5
1740	530	(504)	51.1
1775	540	(513)	51.7
1810	550	(523)	52.3
1845	560	(532)	53.0
1880	570	(542)	53.6
1920	580	(551)	54.1
1955	590	(561)	54.7
1995	600	(570)	55.2
2030	610	(580)	55.7
2070	620	(589)	56.3
2105	630	(599)	56.8
2145	640	(608)	57.3
2180	650	(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

2. HV, HRC, HBS hardness chart

High voltage	CDH	HBS
940	68
920	67.5
900	67
880	66.4
860	65.9
840	65.3
820	64.7
800	64
780	63.3
760	62.5
740	61.8
720	61
700	60.1
690	59.7
680	59.2
670	58.8
660	58.3
650	57.8
640	57.3
630	56.8
620	56.3
610	55.7
600	55.2
590	54.7
580	54.1
570	53.6
560	53
550	52.3	505
540	51.7	496
530	51.1	488
520	50.5	480
510	49.8	473
500	49.1	465
490	48.4	456
480	47.7	448
470	46.9	441
460	46.1	433
450	45.3	425
440	44.5	415
430	43.6	405
420	42.7	397
410	41.8	388
400	40.8	379
390	39.8	369
380	38.8	360
370	37.7	350
360	36.6	341
350	35.5	331
340	34.4	322
330	33.3	313
320	32.2	303
310	31	294
300	29.8	284
295	29.2	280
290	28.5	275
285	27.8	270
280	27.1	265
275	26.4	261
270	25.6	256
265	24.8	252
260	24	247
255	23.1	243
250	22.2	238
245	21.3	233
240	20.3	228
230	18
220	15.7
210	13.4
200	11
190	8.5
180	6
170	3
160	0

3. Hardness table HLD, HRC, HRB, HV, HB, HSD

Leebe DAN	Rockwell CDH	Rockwell HRB	Vickers High voltage	Brinell HB(1)	Brinell HB(2)	Coast HD
300			83
302			84
304			85
306			85
308			86
310			87
312			87
314			88
316			89
318			90
320			90
322			91
324			92
326			93
328			94
330			94
332			95
334			96
336			97
338			98
340			99
342			100
344			101
346			101
348			102
350		59.6	103
352		60.3	104
354		61	105
356		61.7	106
358		62.4	107
360		63.1	108
362		63.8	109
364		64.5	110
366		65.1	111
368		65.8	112
370		66.4	114
372		67	115
374		67.7	116
376		68.3	117
378		68.9	118
380		69.5	119
382		70.1	120
384		70.6	121
386		71.2	123
388		71.8	124
390		72.3	125
392		72.9	126
394		73.4	127
396		74	129
398		74.5	130
400		75	131		142
402		75.5	133		144
404		76	134		145
406		76.5	135		147
408		77	136		149
410		77.5	138		150
412		78	139		152
414		78.4	141		153
416		78.9	142		155
418		79.3	143		156
420		79.8	145	140	157
422		80.2	146	141	159
424		80.7	148	143	160
426		81.1	149	144	162
428		81.5	151	145	163
430		81.9	152	147	165
432		82.4	154	148	166
434		82.8	155	150	168
436		83.2	157	151	169
438		83.6	158	153	171
440		84	160	154	172
442		84.4	161	156	174
444		84.8	163	157	175
446		85.1	164	159	176
448		85.5	166	160	178
450		85.9	168	162	179
452		86.3	169	164	181
454		86.6	171	165	182
456		87	173	167	184
458		87.4	174	168	185
460		87.7	176	170	187	26.4
462		88.1	178	172	188	26.7
464		88.5	179	173	190	27
466		88.8	181	175	191	27.3
468		89.2	183	177	193	27.6
470		89.5	185	178	194	27.9
472		89.9	186	180	196	28.2
474		90.3	188	182	197	28.5
476		90.6	190	184	198	28.8
478		91	192	185	200	29.1
480		91.3	194	187	202	29.4
482		91.7	195	189	203	29.7
484		92.1	197	191	205	30
486		92.4	199	192	206	30.3
488		92.8	201	194	208	30.6
490		93.1	203	196	209	30.9
492		93.5	205	198	211	31.2
494		93.9	207	200	212	31.5
496		94.3	209	202	214	31.7
498		94.6	211	204	215	32
500		95	213	205	217	32.2
502		95.4	215	207	219	32.5
504		95.8	217	209	220	32.8
506		96.2	219	211	222	33.1
508		96.6	221	213	224	33.3
510	19.8	97	223	215	225	33.6
512	20.2	97.4	225	217	227	33.9
514	20.6	97.9	227	219	229	34.2
516	21	98.3	229	221	230	34.4
518	21.3	98.7	231	223	232	34.7
520	21.7	99.2	233	225	234	35
522	22	99.6	235	227	235	35.3
524	22.4		237	229	237	35.6
526	22.8		239	231	239	35.8
528	23.1		241	234	241	36.1
530	23.5		244	236	242	36.4
532	23.8		246	238	244	36.7
534	24.1		248	240	246	37
536	24.5		250	242	248	37.3
538	24.8		252	244	250	37.6
540	25.2		255	246	252	37.9
542	25.5		257	249	254	38.1
544	25.8		259	251	256	38.4
546	26.2		261	253	258	38.7
548	26.5		264	255	259	39
550	26.8		266	258	261	39.3
552	27.1		268	262	263	39.6
554	27.5		270	262	265	39.9
556	27.8		273	265	268	40.2
558	28.1		275	267	270	40.5
560	28.4		278	269	272	40.8
562	28.8		280	272	274	41.1
564	29.1		282	274	276	41.4
566	29.4		285	276	278	41.7
568	29.7		287	279	280	42
570	30		290	281	282	42.3
572	30.3		292	283	285	42.6
574	30.6		294	286	287	42.9
576	30.9		297	288	289	43.2
578	31.2		299	291	292	43.5
580	31.5		302	293	294	43.8
582	31.8		304	296	296	44.1
584	32.1		307	298	299	44.4
586	32.4		309	301	301	44.7
588	32.7		312	303	304	45
590	33		315	306	308	45.4
592	33.3		317	308	310	45.7
594	33.6		320	311	313	46
596	33.9		322	314	315	46.3
598	34.2		325	316	318	46.6
600	34.5		328	319	320	46.9
602	34.8		330	322	323	47.2
604	35.1		333	324	325	47.5
606	35.4		336	327	328	47.8
608	35.7		338	330	331	48.2
610	35.9		341	332	333	48.5
612	36.2		344	335	336	48.8
614	36.5		346	338	339	49.1
616	36.8		349	340	341	49.4
618	37.1		352	343	344	49.7
620	37.4		355	346	346	50.1
622	37.6		357	349	349	50.4
624	37.9		360	351	352	50.7
626	38.2		363	354	355	51
628	38.5		366	357	357	51.3
630	38.7		369	360	360	51.7
632	39		372	363	363	52
634	39.3		375	366	366	52.3
636	39.6		377	369	369	52.6
638	39.8		380	371	371	52.9
640	40.1		383	374	374	53.3
642	40.4		386	377	377	53.6
644	40.7		389	380	380	53.9
646	40.9		392	383	383	54.2
648	41.2		395	386	386	54.6
650	41.5		398	389	389	54.9
652	41.7		401	392	392	55.2
654	42		404	395	395	55.6
656	42.3		407	398	398	55.8
658	42.6		411	401	401	56.2
660	42.8		414	404	404	56.5
662	43.1		417	407	407	56.9
664	43.4		420	410	410	57.2
666	43.6		423	413	413	57.5
668	43.9		426	417	417	57.9
670	44.1		429	420	420	58.2
672	44.4		433	423	423	58.5
674	44.7		436	426	426	58.9
676	44.9		439	429	429	59.2
678	45.2		442	432	432	59.5
680	45.5		446	435	435	59.9
682	45.7		449	439	439	60.2
684	46		452	442	442	60.5
686	46.2		456	445	445	60.9
688	46.5		459	448	448	61.2
690	46.8		463	451	451	61.6
692	47		466	455	455	61.9
694	47.3		469	458	458	62.2
696	47.5		473	461	461	62.6
698	47.8		476	465	465	62.9
700	48		480	468	468	63.3
702	48.3		483	471	471	63.6
704	48.6		487	474	474	64
706	48.8		491	478	478	64.3
708	49.1		494	481	481	64.6
710	49.3		498	485	485	65
712	49.6		501	488	488	65.3
714	49.8		505	491	491	65.7
716	50.1		509	495	495	66
718	50.3		513	498	498	66.4
720	50.6		516	502	502	66.7
722	50.8		520	505	505	67.1
724	51.1		524	508	508	67.4
726	51.3		528	512	512	67.8
728	51.6		532	515	515	68.2
730	51.8		535	519	519	68.5
732	52.1		539	522	522	68.9
734	52.3		543	526	526	69.2
736	52.6		547	529	529	69.6
738	52.8		551	533	533	69.9
740	53.1		555	536	536	70.3
742	53.3		559	540	540	70.7
744	53.6		563	543	543	71
746	53.8		568	547	547	71.4
748	54.1		572	551	551	71.8
750	54.3		576	554	554	72.1
752	54.5		580	558	558	72.5
754	54.8		584	561	561	72.9
756	55		589	565	565	73.2
758	55.3		593	569	569	73.6
760	55.5		597	572	572	74
762	55.7		602	576	576	74.3
764	56		606	580	580	74.7
766	56.2		610	583	583	75.1
768	56.5		615	587	587	75.5
770	56.7		619	591	591	75.8
772	56.9		624	594	594	76.2
774	57.2		628	598	598	76.6
776	57.4		633	602	602	77
778	57.6		638	605	605	77.4
780	57.9		642	609	609	77.7
782	58.1		647	613	613	78.1
784	58.3		652	617	617	78.5
786	58.6		657	620	620	78.9
788	58.8		662	624	624	79.3
790	59		666	628	628	79.7
792	59.2		671	632	632	80.1
794	59.5		676	635	635	80.5
796	59.7		681	639	639	80.9
798	59.9		686	643	643	81.2
800	60.1		691	647	647	81.6
802	60.4		697	651	651	82
804	60.6		702			82.4
806	60.8		707			82.8
808	61		712			83.2
810	61.2		718			83.7
812	61.4		723			84.1
814	61.7		728			84.5
816	61.9		734			84.9
818	62.1		739			85.3
820	62.3		745			85.7
822	62.5		750			86.1
824	62.7		756			86.5
826	62.9		762			87
828	63.1		768			87.4
830	63.3		773			87.8
832	63.5		779			88.2
834	63.7		785			88.6
836	63.9		791			89.1
838	64.1		797			89.5
840	64.3		803			89.9
842	64.5		809			90.4
844	64.7		816			90.8
846	64.9		822			91.2
848	65.1		828			91.7
850	65.3		835			92.1
852	65.4		841			92.6
854	65.6		848			93
856	65.8		854			93.5
858	66		861			93.9
860	66.2		867			94.4
862	66.3		874			94.8
864	66.5		881			95.3
866	66.7		888			95.7
868	66.8		895			96.2
870	67		902			96.7
872	67.2		909			97.1
874	67.3		916			97.6
876	67.5		923			98.1
878	67.6		931			98.6
880	67.8		938			99
882	68		946			99.5
884	68.1		953
886	68.2		961
888	68.4		968
890	68.5		976

Steel Hardness Values ​​Conversion

Approximate values ​​for converting the Vickers hardness of steel (HV) to other hardness and strength measurements.

Vickers hardness	Brinell hardness		Rockwell hardness				Surface Rockwell Hardness			Shore hardness	Tensile strength (approximate value)	Vickers hardness
	10mm steel ball 3,000 kg load						Surface Diamond Cone Indenter
	Standard Steel Ball	Tungsten Carbide Steel Ball	A scale	·Scale	·Scale	·Scale	15-N	30-N	45-N		MPa (1000 psi)
			60 kg load	100 kg load	100 kg load	100 kg load	Scale	Scale	Scale
			Diamond Cone Indenter	Diamond Cone Indenter	Diamond Cone Indenter	Diamond Cone Indenter	15－kg load	30 kg load	45 kg load
High voltage	HBS	HBW	HR	HRB	CDH	HR	HR15N	HR30N	HR45N	SH	σb	High voltage
1	two	3	4	5	6	7	8	9	10	11	12	13
370	350	350	69.2	－	37.7	53.6	79.2	57.4	40.4	－	1170(170)	370
360	341	341	68.7	-109	36.6	52.8	78.6	56.4	39.1	50	1130(164)	360
350	331	331	68.1	－	35.5	51.9	78	55.4	37.8	－	1095(159)	350
340	322	322	67.6	-108	34.4	51.1	77.4	54.4	36.5	47	1070(155)	340
330	313	313	67	－	33.3	50.2	76.8	53.6	35.2	－	1035(150)	330
320	303	303	66.4	-107	32.3	49.4	76.2	52.3	33.9	45	1005(146)	320
310	294	294	65.8	－	31	48.4	75.6	51.3	32.5	－	980(142)	310
300	284	284	65.2	-105.5	29.8	47.5	74.9	50.2	31.1	42	950(138)	300
295	280	280	65.8	－	29.2	47.1	74.6	49.7	30.4	－	935(136)	295
290	275	275	64.5	-104.5	28.5	46.5	74.2	49	29.5	41	915(133)	290
285	270	270	64.2	－	27.8	46	73.8	48.4	28.7	－	905(131)	285
280	265	265	63.8	-103.5	27.1	45.3	73.4	47.8	27.9	40	890(129)	280
275	261	261	63.5	－	26.4	44.9	73	47.2	27.1	－	875(127)	275
270	256	256	63.1	-102	25.6	44.3	72.6	46.4	26.2	38	855(124)	270
265	252	252	62.7	－	24.8	43.7	72.1	45.7	25.2	－	840(122)	265
260	247	247	62.4	-101	24	43.1	71.6	45	24.3	37	825(120)	260
255	243	243	62	－	23.1	42.2	71.1	44.2	23.2	-36	805(117)	255
250	238	238	61.6	99.5	22.2	41.7	70.6	43.4	22.2	－	795(115)	250
245	233	233	61.2	－	21.3	41.1	70.1	42.5	21.1	34	780(113)	245
240	228	228	60.7	98.1	20.3	40.3	69.6	41.7	19.9	33	765(111)	240
230	219	219	－	96.7	-18	－	－	－	－	32	730(106)	230
220	209	209	－	95	-15.7	－	－	－	－	30	695(101)	220
210	200	200	－	93.4	-13.4	－	－	－	－	29	670(97)	210
200	190	190	－	91.5	-11	－	－	－	－	28	635(92)	200
190	181	181	－	89.5	-8.5	－	－	－	－	26	605(88)	190
180	171	171	－	87.1	-6	－	－	－	－	25	580(84)	180
170	162	162	－	85	-3	－	－	－	－	24	545(79)	170
160	152	152	－	81.7	0	－	－	－	－	22	515(75)	160
150	143	143	－	78.7	－	－	－	－	－	21	490(71)	150
140	133	133	–	75	－	－	－	－	－	20	455(66)	140
130	124	124	–	71.2	－	－	－	－	－	－	425(62)	130
120	114	114	－	66.7	－	－	－	－	－	－	390(57)	120
110	105	105	－	62.3	－	－	－	－	－	－	－	110
100	95	95	－	56.2	－	－	－	－	－	－	－	100
95	90	90	－	52	－	－	－	－	－	－	－	95
90	86	86	－	48	－	－	－	－	－	－	－	90
85	81	81	－	41	－	－	－	－	－		－	85

• a) The values ​​represented in bold in this table are aligned with the hardness conversion values ​​according to the ASTM-E140 table above, listed by the respective SAE-ASM-ASTM association.
• b) Numerical values ​​in parentheses are outside the range and are provided for reference only.

Hardness Conversion Formulas

1. Shore Hardness (HS) = Brinell Hardness (BHN) / 10 + 12
2. Shore Hardness (HS) = Rockwell Hardness (HRC) + 15
3. Brinell Hardness (BHN) = Vickers Hardness (HV)
4. Rockwell Hardness (HRC) = Brinell Hardness (BHN) / 10 – 3

Rockwell Hardness (HRC) vs Brinell Hardness (HB)

Hardness is a performance indicator that measures the degree of softness or hardness of a material. There are many methods for hardness testing, each with different principles, leading to different hardness values ​​and meanings.

The most common is static load indentation hardness testing, such as Brinell Hardness (HB), Rockwell Hardness (HRA, HRB, HRC) and Vickers Hardness (HV).

These hardness values ​​indicate the ability of a material surface to resist indentation from a hard object.

The popular Leeb Hardness (HL) and Shore Hardness (HS) belong to the rebound hardness tests, representing the size of the metal's elastic deformation work.

Therefore, hardness is not a simple physical quantity, but a comprehensive performance indicator that reflects the elasticity, plasticity, strength and toughness of a material.

1. Hardness of Steel: The symbol for the hardness of the metal (Hardness) is H.

Depending on the test method used,

• Conventionally, there are Brinell (HB), Rockwell (HRC), Vickers (HV) and Leeb (HL) hardness measurements, among which HB and HRC are most commonly used.
• HB has a wide range of applications, while HRC is suitable for materials with high surface hardness such as heat treatment hardness. The difference between them is in the indenter used in the durometer; the Brinell hardness tester uses a steel ball, while the Rockwell hardness tester uses a diamond.
• HV is used for microscopic analysis. Vickers hardness (HV) is determined by pressing a square diamond cone with a load of up to 120kg and a top angle of 136° into the surface of the material and then dividing the surface area of ​​the indentation pit by the value of the load to get the Vickers. hardness value (HV).
• The HL portable hardness tester is easy to measure. It calculates hardness by using an impact ball to bounce off the hardness surface and the formula for Leeb Hardness HL = 1000 × VB (rebound velocity) / VA (impact velocity).
• The most commonly used portable Leeb hardness tester can convert Leeb (HL) measurements to Brinell (HB), Rockwell (HRC), Vickers (HV), and Shore (HS) hardness. Or use the Leeb principle to directly measure hardness values ​​with Brinell (HB), Rockwell (HRC), Vickers (HV), Leeb (HL), Shore (HS).

Rockwell hardness (HRC) is generally used for materials with high hardness, such as those after heat treatment.

2. HB – Brinell Hardness

It is generally used when the material is softer, such as non-ferrous metals or steel before heat treatment or after annealing. Brinell hardness (HB) is measured by applying a given test load to press a hardened steel ball or carbide ball of a given diameter into the surface of the metal being tested, holding it for a specified time, then unloading and measuring the diameter of the indentation on the tested surface.

The Brinell Hardness value is obtained by dividing the load by the spherical surface area of ​​the indentation.

Typically, a certain load (generally 3,000 kg) is used to press a hardened steel ball of a certain size (generally 10 mm in diameter) onto the surface of the material, held for a period of time, and after discharge, the proportion of load for the indentation area is the Brinell Hardness (HB) value, with units in kilogram-force/mm2 (N/mm ² ).

3. Rockwell hardness uses the depth of plastic deformation of the indentation to determine the hardness value index.

One unit of hardness is 0.002 millimeters. When HB>450 or the sample is too small, Brinell hardness test cannot be used and Rockwell hardness measurement is adopted. This involves using a diamond cone with an apex angle of 120° or a steel ball with a diameter of 1.59 or 3.18 mm, under a given load, pressed into the surface of the material, and determining the hardness of the material. material from the depth of the indentation. According to the different hardness of the testing material, three different scales are used:

• HRA: Uses a 60kg load and a diamond cone indenter to determine hardness, and is used for materials with extremely high hardness (such as hard alloys, etc.).
• HRB: Uses a load of 100kg and a hardened steel ball with a diameter of 1.58mm to determine hardness, and is used for materials with lower hardness (such as annealed steel, cast iron, etc.).
• HRC: It uses a load of 150kg and a diamond cone indenter to determine hardness, and is used for materials with very high hardness (such as hardened steel, etc.).

Additionally:

• HRC implies Rockwell hardness scale C.
• HRC and HB are widely used in production.
• The applicable HRC range is HRC 20-67, equivalent to HB225-650.

If hardness exceeds this range, use the Rockwell Hardness Scale A (HRA).

If the hardness is below this range, use the B Rockwell hardness scale (HRB).

The upper limit of Brinell hardness is HB650; cannot exceed this value.

4. The indenter for Rockwell hardness tester C scale is a diamond cone with an apex angle of 120 degrees. The test load is a fixed value and the Chinese standard is 150 kilograms of force. The indenter for the Brinell hardness tester is a hardened steel ball (HBS) or a hard alloy ball (HBW). The test load varies with the diameter of the sphere, ranging from 3,000 to 31.25 kilograms of force.

5. The indentation of Rockwell hardness is very small and the measurement value is local, so the average value must be calculated by measuring multiple points. It is suitable for finished products and thin sheets and is classified as non-destructive testing. The indentation of Brinell hardness is higher and the measurement value is accurate, but it is not suitable for finished products and thin sheets. It is generally not classified as non-destructive testing.

6. The Rockwell hardness value is a dimensionless number, with no unit. (Therefore, it is incorrect to refer to Rockwell hardness as a degree.) Brinell hardness value has one unit and has a certain approximate relationship with tensile strength.

7. Rockwell hardness is displayed directly on the dial and can also be displayed digitally. It is convenient to operate, fast and intuitive, and suitable for mass production. Brinell hardness requires using a microscope to measure the indentation diameter and then referring to the table or calculating, the operation is relatively complicated.

8. Under certain conditions, HB and HRC can be converted by consulting a table. The mental calculation formula can be remembered approximately as: 1HRC≈1/10HB.

Hardness Test

Hardness is a critical property of materials, particularly in industrial and engineering applications. It refers to the measure of a material's resistance to deformation, especially plastic deformation, when subjected to a force. In simpler terms, hardness indicates a material's ability to resist penetration, scratching, or wear. This attribute is crucial in evaluating the performance and durability of materials used in different environments.

There are several scales and methods of measuring hardness, but the most commonly used include HLD, HRC, HRB, HV, HB, and HSD. Each of these measurements tests different aspects of a material's resistance to forces or deformation using specific testing techniques and machinery. It is important to understand the various hardness scales as they can provide different results and are best suited for specific types of materials.

HLD, or Leeb Hardness, is a dynamic hardness test that measures the rebound speed of a small impact body after being struck against the material under test. The higher the recovery speed, the harder the material. HLD is used for in-situ testing of large and heavy components.

HRC, HRB, and other Rockwell hardness scales utilize a small indenter to create an indentation in the surface of the material under a predetermined force. The depth of the indentation is measured, giving us an indication of the hardness. Hardness values ​​are represented as 0-100 HRC, 0-100 HRB, and so on. Rockwell hardness is typically used to evaluate harder metals and materials.

HV represents Vickers hardness and employs a diamond pyramid indenter with a load applied to create a small indentation in the surface of the material. The dimensions of the indentation are then measured, which reveals the hardness value of the material. Vickers hardness is suitable for materials with various hardness levels and thicknesses, including ceramics and thin metal coatings.

HB stands for Brinell Hardness and uses a spherical indenter under a specific load pushed into the material. The diameter of the left recess is measured to determine the hardness of the material. Brinell hardness is commonly used for softer materials such as aluminum, brass, and certain types of steel.

Lastly, HSD is an abbreviation for Hardness Scleroscope – a less common hardness testing method that operates on the principle of measuring the rebound height of a diamond-tipped hammer after it impacts the surface of the material.

Selecting the appropriate hardness measurement method is crucial to obtaining accurate results and evaluating material performance. It is essential to consider specific material properties, industry requirements and application needs to make informed decisions when selecting hardness measurement methods.

What are the common sources of errors in hardness testing and how can these errors be reduced?

Common sources of errors in hardness testing mainly include errors by the hardness tester itself, changes in testing conditions, and technical errors by the operator. Specifically, the sources of error in Rockwell hardness testing can be divided into three main categories: the first category is problems with the hardness tester itself, such as testing force, indenter shape position error, and measurement structure error; the second category of errors arises from changes in test conditions; The third category of errors originates from technical errors by the operator. Sources of error in Vickers hardness testing include the operator's targeting and reading of indentation diagonals, which may be erroneous, and differences in results that may arise from different people using different measuring devices.

To reduce these errors, the following measures can be taken:

For errors of the hardness tester itself, they can be reduced through regular calibration and maintenance. For example, for Rockwell hardness testers, make sure your parts do not deform or move to avoid errors caused by hardness parameters exceeding specified standards.

Improve testing conditions, such as increasing the surface roughness, weight and coupling degree of the workpiece, especially when measuring Brinell hardness. For special materials such as thin boards, apply an even layer of butter or petroleum jelly to the back to improve the coupling effect.

Reduce operator technical errors. Fully automatic Vickers hardness testers can largely eliminate human error by reducing dependence on targeting and reading indentation diagonals.

Use suitable hardness testers for testing. For example, for small parts, choose a suitable hardness tester and take corresponding measures to reduce errors, such as avoiding side impact on hollow materials.

Through these measures, errors in hardness testing can be effectively reduced, improving the accuracy and reliability of test results.