The Ultimate Guide to Metal Hardness (with Chart)

Are you curious about the hardness of metals and minerals?

Do you want to learn more about the different types of hardness tests and how they are used to measure a material’s resistance to deformation?

Look no further than this comprehensive guide on metal hardness from MachineMfg.

From scratch hardness testing to rebound hardness testing, this article covers all the different methods used to evaluate the hardness of metals and minerals.

You’ll learn about the various types of indentation hardness tests, including Brinell hardness, Rockwell hardness, Vickers hardness, and micro-hardness, and how they differ in terms of the indenter used, the applied load, and the duration of the load.

In addition to detailed explanations of the different hardness tests, this article also includes a handy chart of non-ferrous metal hardness, with information on tensile strength, Rockwell surface, Vickers, Brinell, and more.

Whether you’re a materials scientist, engineer, or just someone with a general interest in the properties of metals and minerals, this article is a must-read.

So dive in and discover everything you need to know about metal hardness!

What Is Metal Hardness?

Hardness is a metric that measures a material’s resistance to local deformations, such as plastic deformation, indentations, or scratches.

It is a crucial factor in determining the hardness of a material.

Types of Metal Hardness

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

① Scratch hardness

Hardness is primarily utilized to compare the resistance to local deformation of various minerals.

The process involves using a rod with a hard and soft end to test the material by sliding it along the rod.

The material’s softness or hardness is determined based on the length of the scratch it leaves on the rod.

Typically, scratches made by harder materials are longer and those made by softer materials are shorter.

② Indentation hardness

Indentation hardness testing is primarily used to evaluate metal materials. It involves applying a specified indenter to the surface of the material under test with a specific load.

The material’s hardness is determined by comparing the amount of local plastic deformation on the material’s surface.

There are several types of indentation hardness tests, including Brinell hardness, Rockwell hardness, Vickers hardness, and micro-hardness, which differ in terms of the indenter used, the applied load, and the duration of the load.

③ Rebound hardness

Rebound hardness testing is primarily used for metal materials. The method involves using a special small hammer that is dropped from a specific height to impact the material sample being tested.

The material’s hardness is determined by the amount of strain energy stored in and then released from the sample during the impact, which is measured by the rebound height of the hammer.

Metal Hardness Chart

Metals Mohs Hardness Chart

The Mohs hardness is a standard for representing mineral hardness, first proposed in 1822 by German mineralogist Frederich Mohs. It is a standard used in mineralogy or gemology. Mohs hardness is determined by using a diamond pyramid needle to scratch the surface of the tested mineral and measure the depth of the scratch. The depth of this scratch is the Mohs hardness, represented by the symbol HM. It is also used to indicate the hardness of other materials.

The depth of the measured scratch is divided into ten levels to represent hardness (scratch method): talc 1 (smallest hardness), gypsum 2, calcite 3, fluorite 4, apatite 5, orthoclase (feldspar) 6, quartz 7, topaz 8, corundum 9, diamond 10. The hardness of the tested mineral is determined by comparing scratches with the standard minerals in the Mohs hardness tester. Although the measurement of this method is rough, it is convenient and practical. It is often used to measure the hardness of natural minerals.

Hardness values are not absolute hardness values, but values represented in order of hardness.

Common Metal Material Hardness Chart

No.	Material Code	Strength Grade	Hardness Value（HB）
01	1Cr13	440（45）	197～229
01	1Cr13	355	187～229
02	1Cr12Mo	550	229～255
02	1Cr12Mo	450	197～229
03	Cr11MoV	490（50）	217～248
		390	192～241
		590	235～269
04	Cr12WMoV	590	235～269
04	Cr12WMoV	690	269～302
05	2Cr12NiMoWV	760	293～331
06	ZG20CrMoV	310	140～201
07	25Cr2MoVA	590	241～277
07	25Cr2MoVA	735	269～302
08	30Cr2MoV	440	179～229
		590	241～277
		735	269～302
09	38CrMoAl	590	241～277
		685	277～302
		785	293～321
10	A3	Hardness after Nitriding Component Normalizing	<131
11	15#		<143
12	25#		<170
13	ZG25		<170
14	20CrA		<179
15	12CrNi3A		<252
16	2Cr13	490	217～248
16	2Cr13	590	235～269
17	2Cr12NiW1Mo1V	735	285～302
18	0Cr17Ni4Cu4Nb	590	262～302
18	0Cr17Ni4Cu4Nb	760	277～311
19	Cr5Mo	/	248～302
20	GH132（GBn181-82）	/	284～349
21	GH136（GBn181-82）	/	298～390
22	R-26	550	262～331
23	3Cr13	590	235～269
23	3Cr13	685	269～302
23	3Cr13	785	286～321
24	1Cr18Ni9Ti	205（225）	≦187
25	0Cr18Ni9	205	≦187
26	1Cr18Ni9	205	≦187
27	Cr15Ni3Bw3Ti	390	207～255
28	34CrMo1A	490（590）	/
29	30Cr2MoV	590	241～277
		690	256～287
		735	269～302
30	34CrNi3Mo	590	220～260
		690	240～282
		735	255～284
		785	271～298
31	30Cr2Ni4MoV	550	207～262
		690	241～302
		760	262～321
		830	285～341
32	15CrMoA	245	131～163
32	15CrMoA	490	207～241
33	15Cr1Mo	275	≦207
34	12Cr1MoVA	245	131～163
35	12Cr2Mo1	275	≦197
35	12Cr2Mo1	315	≦207
36	15Cr1Mo1VA	325	146～196
37	25#	235（215）	110～170
38	30#	265	≦187
39	35#	265	156～217
		255	140～187
		235	121～187
40	45#	295	162～217
		285	149～217
		440	197～229
		345	217～255
41	15CrMoA	245	131～163
41	15CrMoA	490	207～241
42	20MnMo	350	149～217
43	40CrNi3MoA	550	207～262
43	40CrNi3MoA	690	241～302
44	15CrMoA	490	207～241
45	40CrA	390	192～223
45	40CrA	490	217～235
		590	241～277
		685	269～302
46	40CrNi2MoA	540	207～269
		640	248～277
		785	269～321
47	35CrMoA	490	217～255
47	35CrMoA	590	241～277
48	40CrNiMoA	690	255～293
49	20Cr1Mo1VtiB	690	255～293
50	30Cr1Mo1V	590	241～277
51	30Cr1Mo1V	690	255～285

Hardness Conversion Table for Common Metals (such as Carbon Steel, Alloy Steel, etc.)

Rockwell hardness				Surface Rockwell hardness			Vickers	Brinell	Shore
HRA	HRB	HRC	HRD	15N	30N	45N	HV	HB	HS
60kgf	100kgf	150kgf	100kgf	15kgf	30kgf	45kgf	50kgf	3000kgf	JIS
85.6		68	76.9	93.2	84.4	75.4	940		97.6
85.3		67.5	76.5	93	84	74.3	920		96.4
85		67	76.1	92.9	83.6	74.2	900		95.2
84.7		66.5	75.7	92.7	83.1	73.6	880		94
84.4		65.9	75.3	92.5	82.7	73.1	860		92.8
84.1		65.3	74.8	92.3	82.2	72.2	840		91.5
83.8		64.7	74.3	92.1	81.7	71.8	820		90.2
83.4		64	73.8	91.8	81.1	71	800		88.9
83		63.3	73.3	91.5	80.4	70.2	780		87.5
82.6		62.5	72.6	91.2	79.7	69.4	760		86.2
82.2		61.8	72.1	91	79.1	68.6	740		84.8
81.8		61	71.5	90.7	78.4	67.7	720		83.3
81.3		60.1	70.8	90.3	77.6	66.7	700		81.8
81.1		59.7	70.5	90.1	77.2	66.2	690		81.1
80.8		59.2	70.1	89.8	76.8	65.7	680		80.3
80.6		58.8	69.8	89.7	76.4	65.3	670		79.6
80.3		58.3	69.4	89.5	75.9	64.7	660		78.8
80		57.8	69	89.2	75.5	64.1	650		78
79.8		57.3	68.7	89	75.1	63.5	640		77.2
79.5		56.8	68.3	88.8	74.6	63	630		76.4
79.2		56.3	67.9	88.5	74.2	62.4	620		75.6
78.9		55.7	67.5	88.2	73.6	61.7	610		74.7
78.6		55.2	67	88	73.2	61.2	600		73.9
78.4		54.7	66.7	87.8	72.7	60.5	590		73.1
78		54.1	66.2	87.5	72.1	59.9	580		72.2
77.8		53.6	65.8	87.2	71.7	59.3	570		71.3
77.4		53	65.4	86.9	71.2	58.6	560		70.4
77		52.3	64.8	86.6	70.5	57.8	550	505	69.6
76.7		51.7	64.4	86.3	70	57	540	496	68.7
76.4		51.1	63.9	86	69.5	56.2	530	488	67.7
76.1		50.5	63.5	85.7	69	55.6	520	480	66.8
75.7		49.8	62.9	85.4	68.3	54.7	510	473	65.9
75.3		49.1	62.2	85	67.7	53.9	500	465	64.9
74.9		48.4	61.6	84.7	67.1	53.1	490	456	64
74.5		47.7	61.3	84.3	66.4	52.2	480	448	63
74.1		46.9	60.7	83.9	65.7	51.3	470	441	62
73.6		46.1	60.1	83.6	64.9	50.4	460	433	61
73.3		45.3	59.4	83.2	64.3	49.4	450	425	60
72.8		44.5	58.8	82.8	63.5	48.4	440	415	59
72.3		43.6	58.2	82.3	62.7	47.4	430	405	58
71.8		42.7	57.5	81.8	61.9	46.4	420	397	56.9
71.4		41.8	56.8	81.4	61.1	45.3	410	388	55.9
70.8		40.8	65	81	60.2	44.1	400	379	54.8
70.3		39.8	55.2	80.3	59.3	42.9	390	369	53.7
69.8	110	38.8	54.4	79.8	58.4	41.7	380	360	52.6
69.2		37.7	53.6	79.2	57.4	40.4	370	350	51.5
68.7	109	36.6	52.8	78.6	56.4	39.1	360	341	50.4
68.1		35.5	51.9	78	55.4	37.8	350	331	49.3
67.6	108	34.4	51.1	77.4	54.4	36.5	340	322	48.1
67		33.3	50.2	76.8	53.6	35.2	330	313	47
66.4	107	32.2	49.4	76.2	52.3	33.9	320	303	45.8
65.8		31.6	48.4	75.8	51.8	32.8	310	294	44.6
65.2	105.5	29.8	47.5	74.9	50.2	31.1	300	284	43.4
64.8		29.2	47.1	74.6	49.7	30.4	295	280	42.8
64.5	104.5	28.5	46.5	74.2	49	29.5	290	275	42.2
64.2		27.8	46	73.8	48.4	28.7	285	270	41.6
63.8	103.5	27.1	45.3	73.4	47.8	27.9	280	265	40.9
63.5		26.4	44.9	73	47.2	27.1	275	261	40.3
63.1	102	25.6	44.3	72.6	46.4	26.2	270	256	39.7
62.7		24.8	43.7	72.1	45.7	25.2	265	252	39
62.4	101	24	43.1	71.6	45	24.3	260	247	38.4
62		23.1	42.2	71.1	44.2	23.2	255	243	37.8
61.6	99.5	22.2	41.7	70.6	43.4	22.2	250	238	37.2
61.2		21.3	41.1	70.1	42.5	21.1	245	233	36.5
60.7	98.1	20.3	40.3	69.6	41.7	19.9	240	228	35.9
	96.7	18					230	219	34.1
	95	15.7					220	209	33.2
	93.4	13.4					210	200	31.8
	91.5	11					200	190	30.4
	89.5	8.5					190	181	29
	87.1	6					180	171	27.7
	85	3					170	162	26.5
	81.7	0					160	152	25
	78.7						150	143	23.7
	78						140	133	22.1
	71.2						130	124	20.6
	66.7						120	114	19.1
	62.3						110	105	17.6
	56.2						100	95	16.1

Hardness Conversion Table for Soft Metals (such as Copper and Aluminum)

Rockwell hardness		Surface Rockwell hardness			Vickers hardness
HRB	HRF	15T	30T	45T	HV
100kgf	60kgf	15kgf	30kgf	45kgf	50kgf
93.5	110	90	77.5	66	196
	109.5			65.5	194
93			77	65	192
92.5	109		76.5	64.5	190
92		89.5		64	188
91.5	108.5		76	63.5	186
91			75.5	63	184
90.5	108	89		62.5	182
90	107.5		75	62	180
89			74.5	61.5	178
88.5	107			61	176
88		88.5	74	60.5	174
87.5	106.5		73.5	60	172
87				59.5	170
86	106	88	73	59	168
85.5			72.5	58.5	166
85	105.5		72	58	164
84	105	87.5		57.5	162
83.5			71.5	56.7	160
83	104.5		71	56	158
82	104	87	70.5	55.5	156
81.5	103.5		70	54.5	154
80.5	103			54	152
80		86.5	69.5	53.5	150
79	102.5		69	53	148
78	102		68.5	52.5	146
77.5	101.5	86	68	51.5	144
77	101		67.5	51	142
76	100.5	85.5	67	50	140
75	100		66.5	49	138
74.5	99.5	85	66	48	136
73.5	99		65.5	47.5	134
73	98.5	84.5	65	46.5	132
72	98	84	64.5	45.5	130
71	97.5		63.5	45	128
70	97	83.5	63	44	126
69	96.5		62.5	43	124
68	96	83	62	42	122
67	95.5		61	41	120
66	95	82.5	60.5	40	118
65	94.5	82	60	39	116
64	94	81.5	59.5	38	114
63	93	81	58.5	37	112
62	92.6	80.5	58	35.5	110
61	92		57	34.5	108
59.5	91.2	80	56	33	106
58	90.5	79.5	55	32	104
57	89.8	79	54.5	30.5	102
56	89	78.5	53.5	29.5	100
54	88	78	52.5	28	98
53	87.2	77.5	51.5	26.5	96
61.6	86.6	77	50.5	24.5	94
49.5	85.4	76.5	49	23	92
47.5	84.4	75.5	48	21	90
46	83.5	75	47	19	88
44	82.3	74.5	45.5	17	86
42	81.2	73.5	44	14.5	84
40	80	73	43	12.5	82
37.5	78.6	72	41	10	80
35	77.4	71.5	39.5	7.5	78
32.5	76	70.5	38	4.5	76
30	74.8	70	36	1	74
27.5	73.2	69	34		72
24.5	71.6	68	32		70
21.5	70	67	30		68
18.5	68.5	66	28		66
15.5	66.8	65	25.5		64
12.5	65	63.5	23		62
10	63	62.5	20.5		60
	61	61	18		58
	58.8	60	15		56
	56.5	58.5	12		54
	53.5	57			52
	50.5	55.5			50
	49	54.5			49
	47	53.5			48
	45				47
	43				46
	40				45

Hardness of Metal Materials Used in Power Stations

Materials	Reference Standards and Requirements（HB）	Control Scope（HB）	Note
210C	ASTM A210，≤179	130～179
T1a, 20MoG, STBA12, 15Mo3	ASTM A209,≤153	125～153
T2, T11, T12, T21, T22, 10CrMo910	ASTM A213，≤163	120～163
P2, P11, P12, /P21, P22, 10CrMo910		125～179
P2, P11, P12, /P21P22, 10CrMo910 type pipe fittings		130～197	The lower limit of the weld seam must not be less than that of the base material,upper limit≤241
T23	ASTM A213，≤220	150～220
12Cr2MoWVTiB(G102)		150～220
T24	ASTM A213，≤250	180～250
T/P91, T/P92, T911, T/P122	ASTM A213，≤250ASTM A335，≤250	180～250	The hardness of “P” type pipes refers to that of “T” type pipes.
（T/P91, T/P92, T911, T/P122）Weld Seam		180～270
WB36	ASME code case2353，≤252	180～252	The weld seam must not be less hard than the base material.
A515, A106B, A106C, A672 B70 type pipe fittings		130～197	The lower limit of the weld seam must not be less than the base material, with the upper limit≤241.
12CrMo	GB3077,≤179	120～179
15CrMo	JB4726，118～180(Rm:440～610）JB4726，115～178(Rm:430～600）	118～180115～178
12Cr1MoV	GB3077,≤179	135～179
15Cr1Mo1V		135～180
F2(Forged or Rolled Pipe Fittings, Valves, and Components)	ASTM A182,143～192	143～192
F11，Class 1	ASTM A182,121～174	121～174
F11，Class 2	ASTM A182,143～207	143～207
F11，Class 3	ASTM A182,156～207	156～207
F12，Class 1	ASTM A182,121～174	121～174
F12，Class 2	ASTM A182,143～207	143～207
F22，Class 1	ASTM A182, ≤170	130～170
F22，Class 3	ASTM A182,156～207	156～207
F91	ASTM A182, ≤248	175～248
F92	ASTM A182, ≤269	180～269
F911	ASTM A182, 187～248	187～248
F122	ASTM A182, ≤250	177～250
20 Pressure Vessel Carbon Steel and Low Alloy Steel Forgings	JB4726，106～159	106～159
35 (Note: The Rm in the table refers to the tensile strength of the material, measured in MPa.)	JB4726，136～200(Rm:510～670）JB4726，130～190(Rm:490～640）	136～200130～190
16Mn	JB4726，121～178(Rm:450～600）	121～178
20MnMo	JB4726，156～208(Rm:530～700）JB4726，136～201(Rm:510～680）JB4726，130～196(Rm:490～660）	156～208136～201130～196
35CrMo	JB4726，185～235(Rm:620～790）JB4726，180～223(Rm:610～780）	185～235180～223
0Cr18Ni90Cr17Ni12Mo2	JB4728，139～187(Rm:520)JB4728，131～187(Rm:490)	139～187131～187	Stainless Steel Forgings for Pressure Vessels
1Cr18Ni9	GB1220 ≤187	140～187
0Cr17Ni12Mo2	GB1220 ≤187	140～187
0Cr18Ni11Nb	GB1220 ≤187	140～187
TP304H, TP316H, TP347H	ASTM A213，≤192	140～192
1Cr13		192～211	Moving Blades
2Cr13		212～277	Moving Blades
1Cr11MoV		212～277	Moving Blades
1Cr12MoWV		229～311	Moving Blades
ZG20CrMo	JB／T 7024，135～180	135～180
ZG15Cr1Mo	JB／T 7024，140～220	140～220
ZG15Cr2Mo1	JB／T 7024，140～220	140～220
ZG20CrMoV	JB／T 7024，140～220	140～220
ZG15Cr1Mo1V	JB／T 7024，140～220	140～220
35	DL／T439，146～196	146～196	Bolt
45	DL／T439，187～229	187～229	Bolt
20CrMo	DL／T439，197～241	197～241	Bolt
35CrMo	DL／T439，241～285	241～285	Bolt（Dia.＞50mm）
35CrMo	DL／T439，255～311	255～311	Bolt（Dia.≤50mm）
42CrMo	DL／T439，248～311	248～311	Bolt（Dia.＞65mm）
42CrMo	DL／T439，255～321	255～321	Bolt（Dia.≤65mm）
25Cr2MoV	DL／T439，248～293	248～293	Bolt
25Cr2Mo1V	DL／T439，248～293	248～293	Bolt
20Cr1Mo1V1	DL／T439，248～293	248～293	Bolt
20Cr1Mo1VTiB	DL／T439，255～293	255～293	Bolt
20Cr1Mo1VNbTiB	DL／T439，252～302	252～302	Bolt
20Cr12NiMoWV(C422)	DL／T439，277～331	277～331	Bolt
2Cr12NiW1Mo1V	Eastern Steam Turbine Factory Standard	291～321	Bolt
2Cr11Mo1NiWVNbN	Eastern Steam Turbine Factory Standard	290～321	Bolt
45Cr1MoV	Eastern Steam Turbine Factory Standard	248～293	Bolt
R-26(Ni－Cr－Co Alloy）	DL／T439，262～331	262～331	Bolt
GH445	DL／T439，262～331	262～331	Bolt
ZG20CrMo	JB/T7024，135～180	135～180	Cylinder
ZG15Cr1Mo, ZG15Cr2MoZG20Cr1MoV, ZG15Cr1Mo1V	JB/T7024，140～220	140～220	Cylinder

Non-ferrous Metal Hardness Table

Non-ferrous Metal Hardness								Tensile strength δ_b/MPa
Rockwell		Surface Rockwell			Vickers	Brinell (F/D2=30)		Tensile strength δ_b/MPa
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		Tensile strength
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 testing is the simplest and most straightforward method among mechanical property tests. In order to replace certain mechanical property tests with hardness tests, a relatively accurate conversion relationship between hardness and strength is needed in production.

Experience has shown that there is an approximate corresponding relationship between the various hardness values of metal materials, and between hardness values and strength values. This is because the hardness value is determined by the initial plastic deformation resistance and the continued plastic deformation resistance. The higher the strength of the material, the higher the plastic deformation resistance, and thus the higher the hardness value.

Below is a quick calculator created by our site, based on empirical formulas obtained from experiments. It has practical value, but when accurate data is required, testing is still necessary.

Tensile strength N/mm²	Vickers hardness	Brinell hardness	Rockwell hardness
Rm	HV	HB	HRC
250	80	76
270	85	80.7
285	90	85.2
305	95	90.2
320	100	95
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
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
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
1557	480	456	47
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
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
	740		61.8
	760		62.5
	780		63.3
	800		64
	820		64.7
	840		65.3
	860		65.9
	880		66.4
	900		67
	920		67.5
	940

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

Rockwell	Rockwell	Vickers	Brinell	Tensile strength
HRC	HRA	HV	HB	N/mm²
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	—	—

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.

Note: When considering cutting processing, a general conversion of 1HRC ≈ 10HB applies (the hardness of the workpiece material may vary slightly).

The most commonly used indentation hardness tests for metal materials are Brinell, Rockwell, and Vickers hardness tests.

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

When measuring hardness using the rebound method, the hardness value represents the extent of the metal’s elastic deformation function.

Commonly Used Hardness

Brinell Hardness

The Brinell hardness test uses a ball made of hardened steel or a hard alloy with a diameter of D as the indenter.

A specified test force F is applied to the surface of the material being tested, and after a designated hold time, the test force is removed, leaving an indentation with a diameter of d.

The Brinell hardness value is calculated by dividing the test force by the surface area of the indentation. The symbol for the Brinell hardness value is represented as HBS or HBW.

The difference between HBS and HBW lies in the type of indenter used.

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

HBW, on the other hand, refers to the use of a hard alloy ball as the indenter and is used to measure the Brinell hardness of materials with a value below 650.

Even when the same material and experimental conditions are used, the results of the two tests may vary, with the HBW value typically being higher than the HBS value, and there is no exact quantitative rule to follow.

In 2003, China adopted international standards and discontinued the use of steel ball indenters in favor of hard alloy ball heads.

As a result, HBS was no longer used and all Brinell hardness values are now represented by HBW.

Although HBW is often simply referred to as HB, references to HBS may still be found in literature.

The Brinell hardness measurement method is suitable for testing materials such as cast iron, non-ferrous alloys, and various steels that have undergone annealing or quenching and tempering processes.

However, it is not suitable for testing samples or workpieces that are too hard, too small, too thin, or do not allow for large indentations on the surface.

Rockwell Hardness

The Vickers hardness test uses either a diamond cone with a 120-degree cone apex angle or a hardened steel ball with a diameter of Ø1.588mm or Ø3.176mm as the indenter, along with a specified load.

The sample is subjected to an initial load of 10kgf and a total load of 60, 100, or 150kgf.

After the total load is applied, the hardness is determined by the difference in indentation depth when the main load is removed while retaining the initial load and the indentation depth under the initial load.

The Rockwell hardness test uses three different test forces and three different indenters, resulting in a total of nine possible combinations and corresponding Rockwell hardness scales.

These nine scales are suitable for a wide range of commonly used metal materials.

The three most commonly used Rockwell hardness scales are HRA, HRB, and HRC, with HRC being the most widely utilized.

Table of commonly used Rockwell hardness test specifications

Hardness symbol	Indenter type	Total test force F/N（kgf）	Hardness range	Applications
HRA	120°diamond cone	588.4(60)	20~88	Hard alloy, carbide, shallow case hardening steel and etc.
HRB	Ø1.588mm Quenched steel ball	980.7(100)	20~100	Annealed or normalized steel, aluminum alloy, copper alloy, cast iron
HRC	120°diamond cone	1471(150)	20~70	Hardened steel, quenched and tempered steel, deep case hardening steel

The Rockwell hardness test is appropriate for hardness values ranging from 20-70HRC. If the hardness of the sample is less than 20HRC, it is recommended to use the HRB scale as the sensitivity of the indenter decreases with increased pressure on the conical part.

However, if the hardness of the sample is greater than 67HRC, it is advised to use the HRA scale as the pressure on the tip of the indenter may become too high and result in damage to the diamond and reduced life of the indenter.

The Rockwell hardness test is known for its ease, speed, and minimal indentation, making it ideal for testing the surface of finished products and harder, thinner workpieces.

However, due to the small indentation, the hardness value may fluctuate greatly for materials with uneven structures and hardness, making it less accurate than the Brinell hardness test.

The Rockwell hardness test is commonly used to determine the hardness of materials such as steel, non-ferrous metals, and cemented carbides.

Vickers Hardness

The principle behind the Vickers hardness measurement is similar to that of the Brinell hardness test.

A diamond pyramid-shaped indenter with an angle of 136° is used to apply a specified test force, F, onto the surface of the material being tested.

After a specified holding time, the test force is removed, and the hardness value is calculated as the average pressure on the unit surface area of the regular pyramid-shaped indentation, with the symbol HV.

The Vickers hardness measurement has a wide range, and it can measure materials with a hardness ranging from 10 to 1000 HV. The indentation is small in size.

This measurement method is commonly used to measure thin materials and surface-hardened layers created through carburizing and nitriding.

Leeb Hardness

The Leeb Hardness Test uses a device equipped with a tungsten carbide ball to impact the surface of the test piece, which then rebounds. The speed of the rebound is affected by the hardness of the material being tested.

A permanent magnetic material is installed on the impact device, which produces an electromagnetic signal proportional to the speed of the impact body’s movement. This signal is then converted into a Leeb hardness value by an electronic circuit, represented by the symbol HL.

The Leeb Hardness Tester is a handheld device that does not require a workbench. Its hardness sensor is compact and can be easily operated by hand, making it suitable for testing large, heavy, or complex geometries.

One of the key benefits of the Leeb Hardness Test is that it results in only light surface damage, making it an ideal option for non-destructive testing. It also provides a unique hardness test for all directions, narrow spaces, and special parts.

Hardness Testers

Micro Vickers hardness testing machine

HM series:

Vickers hardness testing machine
HV series:

Rockwell hardness testing machine
HR series:

Portable Leeb hardness tester
HH series:

FAQs About Metal Hardness

How to measure hardness of metal?

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

How to increase metal hardness?

The strength of metal materials can be improved through the following five methods:

1) Conducting a heat treatment process, such as quenching, tempering, normalizing, etc., based on the required performance and structure.

2) Surface shot peening.

3) Grain boundary strengthening.

4) Dislocation strengthening.

5) Precipitation of certain compounds through deformation and aging, which can improve strength.

At what temperature does metal lose hardness?

At temperatures below -200 degrees Celsius, ordinary steel becomes as brittle as glass.

The low temperature reduces the cohesive forces between metal molecules, making the material more rigid and less able to withstand deformation. This increased rigidity causes the metal to become more prone to breaking under external force.

However, it is important to note that the brittleness of the metal is dependent on the specific situation.

For example, materials with a face-centered cubic structure do not undergo a transition from ductile to brittle behavior at low temperatures.

What determines the hardness of a metal?

1）The hardness of a metal is determined by the strength of the bonding between metal atoms.

2）The harder the metal, the stronger the bonding between the metal atoms and the smaller the radius of the metal atoms.

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

4）In general, for main group metals, moving from left to right within the same period, the atomic radius decreases and the number of valence electrons increases, leading to an increase in hardness.

On the other hand, moving from top to bottom within the same main group, the atomic radius increases while the number of valence electrons remains constant, resulting in a decrease in hardness.

5）For transition elements, the atomic radius decreases from left to right, but the number of valence electrons increases first and then decreases, making the trend in hardness less clear-cut than for the main family elements.

However, elements with high hardness are typically found in the middle of the transition elements within the same period.

READ NEXT:

Metal	Element	Hardness (Mohs)
Carbon（diamond）	C	10
Boron	B	9.3
Titanium Carbide	Ti+C	9
Tungsten Carbide	W+C	9
Chromium	Cr	8.5
Tungsten	W	7.5
Vanadium	V	7
Rhenium	Re	7
Osmium	Os	7
Silicon	Si	6.5
Ruthenium	Ru	6.5
Tantalum	Ta	6.5
Iridium	Ir	6.5
Titanium	Ti	6
Manganese	Mn	6
Germanium	Ge	6
Niobium	Nb	6
Rhodium	Rh	6
Uranium	U	6
Beryllium	Be	6
Molybdenum	Mo	5.5
Hafnium	Hf	5.5
Cobalt	Co	5
Zirconium	Zr	5
Palladium	Pd	4.75
White Gold	Au+Ni+Pd	4
Steel	Fe+C	4
Iron	Fe	4
Nickel	Ni	4
Arsenic	As	3.5
Platinum	Pt	3.5
Brass	Cu+Zn	3
Bronze	Cu+Sn	3
Copper	Cu	3
Antimony	Sb	3
Thorium	Th	3
Aluminum	Al	2.75
Magnesium	Mg	2.5
Zinc	Zn	2.5
Silver	Ag	2.5
Lanthanum	La	2.5
Cerium	Ce	2.5
Gold	Au	2.5
Tellurium	Te	2.25
Bismuth	Bi	2.25
Cadmium	Cd	2
Calcium	Ca	1.75
Gallium	Ga	1.5
Strontium	Sr	1.5
Tin	Sn	1.5
Mercury	Hg	1.5
Lead	Pb	1.5
Barium	Ba	1.25
Indium	In	1.2
Thallium	Ti	1.2
Lithium	Li	1.2
Sodium	Na	0.5
Potassium	K	0.4
Rubidium	Rb	0.3
Caesium	Cs	0.2

The Ultimate Guide to Metal Hardness (with Chart)

What Is Metal Hardness?

Types of Metal Hardness