Hardness testing - Roy Mech

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Matter Index Page

Hardness Measurement

Brinell ...... Vickers ...... Rockwell ...... Superficial Rockwell...... Scleroscope......

Knoop...... Jominy...... Moh...... Shore (Durometer)

Equivalent Hardness Table (harder scales)...... Equivalent Hardness Table (softerr scales)

Hardness Comparison chart...... Typical component Surface Hardness......

Methods of Measuring Hardness

Brinell Hardness Test

In this test a hardened steel ball is pressed into the surface of the test material using a prescribed ball. The ball and load have to be selected to suit the material being tested.

The Brinell hardness test consists of indenting the test material with a 10 mm diameter hardened steel or carbide ball subjected to a load of 3000 kgf (29 430 N). For softer materials the load can be reduced to 1500 kgf (14 715 N) or 500 kgf (4 905 N ) to avoid excessive indentation. The full load is normally applied for 10 to 15 seconds for harder ferrous metals and for 30 seconds or more for other metals softer metals. The diameter of the indentation left in the test material is measured with a microscope.

The Brinell hardness number is calculated by dividing the load applied by the surface area of the indentation.

D = Diameter of Ball
D₁ = Diameter of indentation
F = applied force

Vickers Hardness Test

In this test a Diamond Indenter is pressed into the surface of the material being tested. Standard loads used include 5, 10, 20, 30, 50, and 100 kgf. (49,05, 98,1 196,2 490,5 and 981 N).
The load is stated in specifying the hardness number i.e HD(10) = 100. the indenter is a square based pyramid (136^o included angle )to suit the material being tested

The Hardness Number HD = 1.844 x Load/ Average diagonal length of indentation

Rockwell Hardness Test

In this test a Hard Steel Ball or a Diamond Cone Indenter is pressed into the surface of the material being tested/ The result of the test is read directly from machine.

The indenter is forced into the test material under a preliminary minor load (98N)and after equilibrium are achieved an indicating device, which follows the movements of the indenter, is set to the datum position. An additional major load is then applied with resulting increase in penetration. The conditions are then allowed to stabilise and then the additional major load is removed,leaving the minor load in place. The resulting permanent penetration esulting from the application and removal of the additional major load is used to calculate the Rockwell hardness number.

HR = E - e

F1 = additional major
e = permanent increase in depth of penetration due to major load , measured in units of 0.001 mm
E = a constant of 100 units for diamond and ball indenters
HR = Rockwell hardness number
D = diameter of steel ball


Scale	Indenter	Major Load F1 N	E	Applications
A	120^oDiamond cone	490.5	100	Sheet steel ; shallow case hardened
B	1/16" steel ball	882.9	130	Copper, Aluminium alloys, Low Carbon Steel
C	120^oDiamond cone	1373.4	100	Most Widely Used -Hardened Steels, Cast irons etc
D	120^oDiamond cone	882.9	100	Thin but hard steels, Ductile Iron (Pearlitic
E	1/8" steel ball	882.9	130	Cast Iron, Aluminium, Bearings alloys
F	1/16" steel ball	490.5	130	Annealed copper alloys , Soft thin metals
G	1/16" steel ball	1373.4	130	Phosphor bronze, beryllium copper, malleable irons, Lead etc
H	1/8" steel ball	490.5	130	Soft Metals Plastics etc
K	1/8" steel ball	1373.4	130	Soft bearing metals, Plastics, soft materials.
L	1/4" steel ball	490.5	130	Soft bearing metals, Plastics, soft materials.
M	1/4" steel ball	882.9	130	Soft bearing metals, Plastics, soft materials.
P	1/4" steel ball	1373.4	130	Soft bearing metals, Plastics, soft materials.
R	1/2" steel ball	490.5	130	Soft bearing metals, Plastics, soft materials.
S	1/2" steel ball	882.9	130	Soft bearing metals, Plastics, soft materials.
V	1/2" steel ball	1373.4	130	Soft bearing metals, Plastics, soft materials.

Superficial Rockwell Hardness Test

A more surface sensitive measurement of hardness than for the regular Rockwell scales. This technique is useful for samples with hardness gradients at the surface, to test small areas, and for thin samples. Superficial Rockwell hardness scales are N and T for metals and W, X, and Y for non-metallic materials and coatings. The Superficial Rockwell hardness test method consists of indenting the test material with a diamond cone (N scale) or hardened steel ball indenter. The indenter is forced into the test material under a preliminary minor (29.43N) and the conditions are allowed to settle. Then the indicating device that follows the movements of the indenter is set to a datum position. An additional major load, is applied with resulting increase in penetration . The conditions are allowed to settle again and then the additional major load is removed. The permanent increase in depth of penetration, resulting from the application and removal of the additional major load is used to calculate the Rockwell Superficial hardness number.

HR = E - e

e = permanent increase in depth of penetration due to major load F1, measured in units of 0.001 mm
E = a constant of 100 units for diamond and ball indenters
HR = Rockwell hardness number
D = diameter of steel ball


Scale	Indenter	Major Load ( N )	E	Application
15N	120^o Diamond cone	117.72	100	Similar to C scale, but for thin materials
30N	120^o Diamond cone	264.87	100	Same as 15N
45N	120^o Diamond cone	412	100	Same as 15N
15T	1/16" steel ball	117.72	100	Similar to B scale, but for thin materials
30T	1/16" steel ball	264.87	100	Same as 15T
45T	1/16" steel ball	412	100	Same as 15T
15W	1/8" steel ball	117.72	100	For very soft materials
30W	1/8" steel ball	264.87	100	For very soft materials
45W	1/8" steel ball	412	100	For very soft materials
15X	1/4" steel ball	117.72	100	For very soft materials
30X	1/4" steel ball	264.87	100	For very soft materials
45X	1/4" steel ball	412	100	For very soft materials
15Y	1/2" steel ball	117.72	100	For very soft materials
30Y	1/2" steel ball	264.87	100	For very soft materials
45Y	1/2" steel ball	412	100	For very soft materials

The Shore (Scleroscope ) Hardness Test

The Scleroscope test consists of dropping a diamond tipped hammer, which falls inside a glass tube under the force of its own weight from a fixed height, onto the test specimen. The height of the rebound travel of the hammer is measured on a graduated scale. The harder the material, the higher the rebound. The scale of the rebound is arbitrarily chosen and consists on Shore units, divided into 100 parts, which represent the average rebound from pure hardened high-carbon steel. The scale is continued higher than 100 to to allow for metals having greater hardness.

The shore scleroscope test does not normally mark the material under test. The Shore Scleroscope measures hardness in relation to the elasticity of the material.

Advantages of this method are portability and non-marking of the test surface.

Knoop

The Knoop indenter has a polished rhombohedral shape with an included longitudinal angle of 172� 30� and an included transverse angle of 130� 0�. The narrowness of the indenter makes it ideal for testing specimens with steep hardness gradients and coatings. Knoop is a better choice for hardness testing of hard brittle materials.

Jominy Hardenability

The Jominy test involves heating a test specimen of steel 25mm diameter and 100mm long to an austenitising temperature and quenching from one end with a controlled and standardized jet of water. After quenching, the hardness is measured at intervals taken form the quenched end. The hardness gradient along the test surface provides an indication of the material�s hardenability.

Moh's Hardness Scale

The Moh's hardness scale consists of 10 minerals arranged in order from 1 to 10. Diamond is rated as the hardest and is indexed as 10; talc as the softest with index number 1. Each mineral in the scale will scratch all those below it as follows:

Diamond	10
Corundum	9
Topaz	8
Quartz	7
Orthoclase (Feldspar)	6
Aptite	5
Fluorite	4
Calcite	3
Gypsum	2
Talc	1

Shore (Durometer) test

The hardness testing of plastics is most commonly measured by the Shore (Durometer) test.  This test measures the resistance of the plastic toward indentation.   The scale provide an empirical hardness value that doesn't relate directly to the mechanical properties of the material being tested.   Shore Hardness, using either the Shore A or Shore D scale, is the preferred method for rubbers/elastomers and is also commonly used for 'softer' plastics such as polyolefins, fluoropolymers, and vinyls.   The Shore A scale is used for 'softer' rubbers while the Shore D scale is used for 'harder' rubbers.

The Shore hardness is measured with an apparatus known as a Durometer and consequently is also known as 'Durometer hardness'.   The hardness value is determined by the penetration of the Durometer indenter foot into the sample.   If the indenter completely penetrates the sample, a reading of 0 is obtained, and if no penetration occurs, a reading of 100 results.    Because of the resilience of rubbers and plastics, the hardness reading my change over time - so the indentation time is sometimes reported along with the hardness number.   The test method is identified in standard ISO 868.

The results obtained from this test are a useful measure of relative resistance to indentation of various grades of polymers.   However, the Shore Durometer hardness test does not serve well as a predictor of other properties such as strength or resistance to scratches, abrasion, or wear, and should not be used alone for product design specifications.

Tables showing the comparative hardness numbers between scales is provided at site the following sites.....

Equivalent Hardness Conversion Tables

Harder Scales

VPN	ROCKWELL SCALES					ROCKWELL Superficial			BRINELL		SCLERO- SCOPE	U.T.S.
DPH HV/10	A	B	C	D	G	15N	30N	45N	BHN 500kg	BHN 3000kg		MPa
1865	92		80	87		97	92	87
1787	92		79	86		96	92	87
1710	91		78	85		96	91	86
1633	91		77	84		96	91	85
1556	90		76	83		96	90	84
1478	90		75	83		95	89	83
1400	89		74	82		95	89	82
1323	89		73	81		95	88	81
1245	88		72	80		95	87	80
1160	87		71	80		94	87	79
1076	87		70	79		94	86	78			101
1004	86		69	78		94	85	77			99
940	86		68	77		93	84	75			97
900	85		67	76		93	84	74			95
865	85		66	75		93	83	73			92
832	84		65	75		92	82	72		739	91
800	84		64	74		92	81	71		722	88
772	83		63	73		91	80	70		705	87
746	83		62	72		91	79	69		688	85
720	82		61	72		91	79	68		670	83
697	81		60	71		90	78	67		654	81	2206
674	81		59	70		90	77	66		634	80	2137
653	80		58	69		89	76	64		615	78	2069
633	80		57	69		89	75	63		595	76	2000
613	79		56	68		88	74	62		577	75	1944
595	79	120	55	67		88	73	61		560	74	1889
577	78	120	54	66		87	72	60		543	72	1834
560	78	119	53	65		87	71	59		523	71	1772
544	77	119	52	65		86	70	57		512	69	1689
528	77	118	51	64		86	69	56		496	68	1648
513	76	117	50	63		86	69	55		481	67	1607
498	75	117	49	62		85	68	54		469	66	1565
484	75	116	48	61		85	67	53		455	64	1524
471	74	116	47	61		84	66	51		443	63	1496
458	74	115	46	60		84	65	50		432	62	1462
446	73	115	45	59		83	64	49		421	60	1420
434	73	114	44	59		83	63	48		409	58	1379
423	72	113	43	58		82	62	47		400	57	1351
412	72	113	42	57		82	61	46		390	56	1317
402	71	112	41	56		81	60	44		381	55	1289
392	71	112	40	55		80	60	43		371	54	1255
382	70	111	39	55		80	59	42		362	52	1220
372	70	110	38	54		79	58	41		353	51	1193
363	69	110	37	53		79	57	40		344	50	1165
354	69	109	36	52		78	56	38		336	49	1138
345	68	109	35	52		78	55	37		327	48	1103
336	68	108	34	51		77	54	36		319	47	1076
327	67	108	33	50		77	53	35		311	46	1048
318	67	107	32	49		76	52	34		301	44	1014
310	66	106	31	48	91	76	51	33		294	43	993
302	66	105	30	48	91	75	50	31		286	42	965
294	65	104	29	47	89	75	50	30		279	41	945
286	65	104	28	46	88	74	49	29		271	41	917
279	64	103	27	45	87	73	48	28		264	40	889
272	64	103	26	45	86	73	47	27		258	39	869
266	63	102	25	44	85	72	46	26		253	38	855
260	63	101	24	43	84	72	45	24		247	37	834
254	62	100	23	42	83	71	44	23	201	240	36	814
248	62	99	22	42	81	71	43	22	195	234	35	793
243	61	98	21	41	79	70	42	21	189	228	35	772
238	61	97	20	40	78	69	42	20	184	222	34	752

VPN

ROCKWELL SCALES

ROCKWELL Superficial

BRINELL

SCLERO-
SCOPE

U.T.S.

DPH
HV/10

15N

30N

45N

BHN
500kg

BHN
3000kg

MPa

Softer Scales

VPN	ROCKWELL SCALES								ROCKWELL Superficial			BRINELL		SCLERO- SCOPE	U.T.S.
DPH HV/10	A	B	C	E	F	G	H	K	15T	30T	45T	BHN 500kg	BHN 3000kg		MPa
234	60	97	19			77			92	80	69	181	218	34	738
230	59	96	18			76			92	80	68	179	214	33	731
226	59	96	17			75			92	80	68	177	210	33	717
222	58	95	16			74			92	79	67	175	208	32	703
217	58	95	15			73			92	79	67	171	205	31	690
213	58	94	14			73			91	79	66	169	203	31	683
208	57	93	13			71			91	78	66	167	200	30	676
204	57	92	12			70		100	91	78	65	163	195	30	662
200	56	92	11			69		100	91	77	64	162	193	29	655
196	56	91	10			68		100	90	77	64	160	190	28	641
192	56	90	9			66		99	90	76	63	157	185	27	627
188	55	89	8			64		98	90	76	62	154	180	26	607
184	54	88	7			63		97	90	75	61	151	176	26	593
180	54	87	6			61		97	89	75	60	148	172	26	579
176	53	86	5			59		96	89	74	59	145	169	25	572
172	53	85	4			58		95	89	74	58	142	165	25	558
168	52	84	3			56		94	88	73	57	140	162	25	545
164	51	83	2			54		93	88	72	56	137	159	24	538
160	51	82	1			53		92	88	72	55	135	156	24	524
156	50	81	0			51		91	87	71	54	133	153	24	517
152	50	80				49		91	87	70	53	130	150		503
148	49	79				48		90	87	70	52	128	147
144	49	78				46		89	86	69	51	126	144
141	48	77				44		88	86	68	50	124	141
139	47	76				43		87	86	68	49	122	139
137	47	75			100	41		86	85	67	49	120	137
135	46	74			99	39		85	85	66	48	118	135
132	46	73			99	38		85	85	66	47	116	132
130	45	72			98	36		84	84	65	46	114	130
127	45	71		100	98	35		83	84	64	45	112	127
125	44	70		100	97	33		82	84	64	44	110	125
123	44	69		99	96	31		81	83	63	43	109	123
120	43	68		98	96	30		80	83	62	42	107	121
118	43	67		98	95	28		79	83	62	41	106	119
116	42	66		97	95	27		78	82	61	40	104	117
115	42	65		96	94	25		78	82	60	39	102	116
114	42	64		96	94	24		77	82	60	38	101	114
113	41	63		95	93	22		76	81	59	37	99	112
112	41	62		95	92	21		75	81	58	36	98	110
111	40	61		94	92	19		74	81	57	35	96	108
110	40	60		93	91	18		73	81	57	34	95	107
108	39	59		93	91	16		72	80	56	32	94	106
107	39	58		92	90	15		71	80	55	31	92	104
106	38	57		91	90	13		71	80	55	30	91	102
105	38	56		91	89	12		70	79	54	29	90	101
104	38	55		90	88	10		69	79	53	28	89	99
103	37	54		90	88	9		68	79	53	27	87
102	37	53		89	87	7		67	78	52	26	86
101	36	52		88	87	6		66	78	51	25	85
100	36	51		88	86	4		65	78	51	24	84
100	35	50		87	86	3		65	77	50	23	83
99	35	49		87	85			64	77	49	22	82
98	35	48		86	85			63	77	49	21	81
97	34	47		85	84			62	76	48	20	80
96	34	46		85	83			61	76	47	19	79
95	33	45		84	83			60	76	46	18	79
95	33	44		84	82			59	75	46	17	78
94	32	43		83	82			58	75	45	16	77
93	32	42		82	81			58	75	44	15	76
92	31	41		82	81			57	74	44	14	75
91	31	40		81	80			56	74	43	13	74
90	31	39		80	79			55	74	42	11	74
90	30	38		80	79			54	73	42	10	73
89	30	37		79	78			53	73	41	9	72
88	29	36		79	78		100	52	73	40	8	71
88	29	35		78	77		100	52	72	40	7	71
87	28	34		77	77		99	51	72	39	6	70
87	28	33		77	76		99	50	72	38	5	69
86	28	32		76	75		99	49	71	38	4	68
86	27	31		76	75		98	48	71	37	3	68
85	27	30		75	74		98	47	71	36	2	67
85	26	29		74	74		98	46	70	36	1	66
84	26	28		74	73		97	45	70	35		66
84	25	27		73	73		97	45	70	34		65
83	25	26		73	72		97	44	69	33		65
83	24	25		72	71		96	42	69	33		64
82	24	24		71	71		96	42	69	32		64
82	24	23		71	70		96	41	68	31		63
81	23	22		70	70		95	40	68	31		63
81	23	21		70	69		95	39	68	30		62
80	22	20		69	69		95	38	68	29		62
80	22	19		68	68		94	38	67	29		61
79	21	18		68	67		94	37	67	28		61
79	21	17		67	67		93	36	67	27		60
78	21	16		67	66		93	35	66	26		60
78	20	15		66	66		93	34	66	26		59
77		14		65	65		92	33	66	25		59
77		13		65	65		92	32	65	24		58
76		12		64	64		92	32	65	24		58
76		11		64	64		91	31	65	23		57
75		10		63	63		91	30	64	22		57
75		9		62	62		91	29	64	22		56
74		8		62	62		90	28	64	21		56
74		7		61	61		90	27	63	20		56
73		6		61	61		90	26	63	20		55
73		5		60	60		89	26	63	19		55
72		4		59	60		89	25	62	18		55
72		3		59	59		88	24	62	17		54
71		2		58	58		88	23	62	17		54
71		1		58	58		88	22	61	16		53
70		0		57	57		87	21	61	15		53
VPN	ROCKWELL SCALES								ROCKWELL Superficial			BRINELL		SCLERO- SCOPE	U.T.S.
DPH HV/10	A	B	C	E	F	G	H	K	15T	30T	45T	BHN 500kg	BHN 3000kg		MPa

Figure comparing hardness scales

Table of Components showing relevant surface Hardness values

Important Notes:
Values below are typical of high specification components.. Lower values are likely in more general applications...

Component	Hardness	Scale

Hardened Track for Roller	670-840	HV
Hardened Machine slideway	70-75	HS
Surface Hardened Gear (High spc'n)	58-63	RC
Modern Rails (Used for Normal traffic)	300-340	HV
Modern Rails (High Duty)	340 -420	HV
Shear Blades	81-85	RC
Carbide Dies (Drawing , Forming etc)	80-92	RA
Mild steel components	120	HV
Wrought iron	102	HV
Axe	600	HV
Fork/Rake	700	HV
Kitchen knife	680	HV
Stainless table knife	550	HV
Hammer Face	660	HV
Chisel	600	HV
File	60-61	RC
Drill Bit HSS	63-65	RC
Drill Bit Cobalt	66-67	RC

Links Providing Relevant Information

Gordon England ..Thermal Spraying Specialist with detailed information on Hardness Testing / Corrosion
Hardness Testers..Equipment supplier with detailed information on Hardness Testing / Corrosion
Materials Co UK - Rubber Hardness Testing..Useful Notes and references
NPL - site search (Hardness Testing )..Authoritative source of information on hardness testing (use search to find)
Cambridge U. Jominy Test..Jominy test examples and notes
Material Hardness..A very detailed document covering most hardness testing methods

Matter Index Page