Hardness and Tensile Strength of Steels: Brinell and Rockwell Scales

Following is an estimate of the relationship between various hardness scales and the tensile strength of standard steels. It should be considered as a general comparison not applicable to all materials:

Hardness Conversion Table

Brinell Hardness	Rockwell Hardness Scales
Tungsten Carbide Ball 3000 KG	A Scale 60 kg	B Scale 100 kg	C Scale 150 kg	Tensile Stength (approx.)
–	86	–	68	–
–	85	–	68	–
–	85	–	67	–
767	85	–	66	–
757	84	–	66	–
745	84	–	65	–
733	84	–	65	–
722	83	–	64	–
712	83	–	64	–
710	83	–	63	–
698	83	–	62	–
684	82	–	62	–
682	82	–	62	–
670	82	–	61	–
656	81	–	60	–
653	81	–	60	–
647	81	–	60	–
638	81	–	59	329,000
630	81	–	59	324,000
627	80	–	59	323,000
601	80	–	57	309,000
578	79	–	56	297,000
555	78	–	55	285,000
534	78	–	54	274,000
514	77	–	52	263,000
495	76	–	51	253,000
477	76	–	50	243,000
461	75	–	48	235,000
444	74	–	47	225,000
429	73	–	46	217,000
415	73	–	44	210,000
401	72	–	43	202,000
388	71	–	42	195,000
375	71	–	40	188,000
363	70	–	39	182,000
352	69	–	38	176,000
341	69	–	37	170,000
331	68	–	36	166,000
321	68	–	34	160,000
311	67	–	33	155,000
302	66	–	32	150,000
293	66	–	31	145,000
285	65	–	30	141,000
277	65	–	29	137,000
269	64	–	28	133,000
262	64	–	27	129,000
255	63	–	25	126,000
248	62	–	24	122,000
241	62	100	23	118,000
235	61	99	22	115,000
229	61	98	20	111,000
223	–	97	20	–
217	–	96	18	105,000
212	–	96	17	102,000
207	–	95	16	100,000
201	–	94	15	98,000
197	–	93	–	95,000
192	–	92	–	93,000
187	–	91	–	90,000
183	–	90	–	89,000
179	–	89	–	87,000
174	–	88	–	85,000
170	–	87	–	83,000
167	–	86	–	81,000
163	–	85	–	79,000
156	–	83	–	76,000
149	–	81	–	73,000
143	–	79	–	71,000
137	–	76	–	67,000
131	–	74	–	65,000
126	–	72	–	63,000
121	–	70	–	60,000
116	–	68	–	58,000
111	–	66	–	56,000

July 24, 2010December 9, 2017

Machinability of Metals

Machinability is the defined as the ease with which a material can be machined. The American Iron and Steel Institute has determined that AISI 1112 Steel has a machinability of 100%. Other materials are compared below:

Carbon Steels

1015 – 72%
1018 – 78%
1020 – 72%
1022 – 78%
1030 – 70%
1040 – 64%
1042 – 64%
1050 – 54%
1095 – 42%
1117 – 91%
1137 – 72%
1141 – 70%
1141 annealed – 81%
1144 – 76%
1144 annealed – 85%
1144 stress-proof – 83%
1212 – 100%
1213 – 136%
12L14 – 170%
1215 – 136%

Alloy Steels

2355 annealed – 70%
4130 annealed – 72%
4140 annealed – 66%
4142 annealed – 66%
41L42 annealed – 77%
4150 annealed – 60%
4340 annealed – 57%
4620 – 66%
4820 annealed – 49%
52100 annealed – 40%
6150 annealed – 60%
8620 – 66%
86L20 – 77%
9310 annealed – 51%

Stainless Steels and Super Alloys

302 annealed – 45%
303 annealed – 78%
304 annealed – 45%
316 annealed – 45%
321 annealed – 36%
347 annealed – 36%
410 annealed – 54%
416 annealed – 110%
420 annealed – 45%
430 annealed – 54%
431 annealed – 45%
440A – 45%
15-5PH condition A – 48%
17-4PH condition A – 48%
A286 aged – 33%
Hastelloy X – 19%

Tool Steels

A-2 – 42%
A-6 – 33%
D-2 – 27%
D-3 – 27%
M-2 – 39%
O-1 – 42%
O-2 – 42%

Gray Cast Iron

ASTM class 20 annealed – 73%
ASTM class 25 – 55%
ASTM class 30 – 48%
ASTM class 35 – 48%
ASTM class 40 – 48%
ASTM class 45 – 36%
ASTM class 50 – 36%

Nodular Ductile Iron

60-40-18 annealed – 61%
65-45-12 annealed – 61%
80-55-06 – 39%

Aluminum / Magnesium Alloys

aluminum, cold drawn – 360%
aluminum, cast – 450%
aluminum, die cast – 76%
magnesium, cold drawn – 480%
magnesium, cast – 480%

July 24, 2010December 9, 2017

Galvanic Corrosion and the Compatibility of Metals – Anodic Index

Designs sometimes cause dissimilar metals to be in contact within an assembly. Increased variance of the two metals’ anodic index cause accelerated corrosion of the more anodic metal. This is called galvanic corrosion. The variance in anodic index can be controlled somewhat through coatings (paint, epoxy, powder coat, etc) and plating (zinc, chrome, etc).

The table below provides a generalize guide for predicting the anodic corrosion two dissimilar metals are prone to. The service environment also plays a role:

For harsh environments: outdoors, high humidity, and salt environments fall into this category. Typically there should be not more than 0.15 V difference in the “Anodic Index”. For example; gold – silver would have a difference of 0.15V being acceptable.
For normal environments: storage in warehouses or non-temperature and humidity controlled environments. Typically there should not be more than 0.25 V difference in the “Anodic Index”.
For controlled environments: where the temperature and humidity controlled, 0.50 V can be tolerated. Caution should be maintained when deciding for this application as humidity and temperature do vary from regions.

Anodic Index

Metallurgy	Index (V)
Gold, solid and plated, Gold-platinum alloy	0.00
Rhodium plated on silver-plated copper	0.05
Silver, solid or plated; monel metal. High nickel-copper alloys	0.15
Nickel, solid or plated, titanium an s alloys, Monel	0.30
Copper, solid or plated; low brasses or bronzes; silver solder; German silvery high copper-nickel alloys; nickel-chromium alloys	0.35
Brass and bronzes	0.40
High brasses and bronzes	0.45
18% chromium type corrosion-resistant steels	0.50
Chromium plated; tin plated; 12% chromium type corrosion-resistant steels	0.60
Tin-plate; tin-lead solder	0.65
Lead, solid or plated; high lead alloys	0.70
Aluminum, wrought alloys of the 2000 Series	0.75
Iron, wrought, gray or malleable, plain carbon and low alloy steels	0.85
Aluminum, wrought alloys other than 2000 Series aluminum, cast alloys of the silicon type	0.90
Aluminum, cast alloys other than silicon type, cadmium, plated and chromate	0.95
Hot-dip-zinc plate; galvanized steel	1.20
Zinc, wrought; zinc-base die-casting alloys; zinc plated	1.25
Magnesium & magnesium-base alloys, cast or wrought	1.75
Beryllium	1.85

July 24, 2010December 9, 2017

Table of Steel Equivalent Grades (EN, SAE/AISI, UNS, DIN, BS, UNI, JIS)

The table below compares steel equivalent grades of materials from various international specifications. Note that materials compared are the nearest available grade and may have slight variations in actual chemistry.

Comparison of steel grades by chemistry
EN #	EN name	SAE	UNS	DIN	BS 970	UNI	JIS
Carbon steels
1.1141 1.0401 1.0453	C15D C18D	1018		CK15 C15 C16.8	040A15 080M15 080A15 EN3B	C15 C16 1C15	S15 S15CK S15C
1.0503 1.1191 1.1193 1.1194	C45	1045		C45 CK45 CF45 CQ45	060A47 080A46 080M46	C45 1C45 C46 C43	S45C S48C
1.0726 1.0727	35S20 45S20	1140/1146		35S20 45S20	212M40 En8M
1.0715 1.0736	11SMn37	1215		9SMn28 9SMn36	230M07 En1A	CF9SMn28 CF9SMn36	SUM 25 SUM 22
1.0718 1.0737	11SMnPb30 11SMnPb37	12L14		9SMnPb28 9SMnPb36	230M07 Leaded En1A Leaded	CF9SMnPb29 CF9SMnPb36	SUM 22L SUM 23L SUM 24L
Alloy steels
1.7218		4130		25CrMo4 GS-25CrMo4	708A30 CDS110	25CrMo4 (KB) 30CrMo4	SCM 420 SCM 430 SCCrM1
1.7223 1.7225 1.7227 1.3563	42CrMo4	4140/4142		41CrMo4 42CrMo4 42CrMoS4 43CrMo4	708M40 708A42 709M40 En19 En19C	41CrMo4 38CrMo4 (KB) G40 CrMo4 42CrMo4	SCM 440 SCM 440H SNB 7 SCM 4M SCM 4
1.6582 1.6562	34CrNiMo6	4340		34CrNiMo6 40NiCrMo8-4	817M40 En24	35NiCrMo6 (KB) 40NiCrMo7 (KB)	SNCM 447 SNB24-1-5
1.6543 1.6523	20NiCrMo2-2	8620		21NiCrMo22 21NiCrMo2	805A20 805M20	20NiCrMo2	SNCM 200 (H)
Stainless steels
1.4310	X10CrNi18-8	301	S30100
1.4318	X2CrNiN18-7	301LN
1.4305	X8CrNiS18-9	303	S30300	X10CrNiS18-9	202S 21 En58M	X10CrNiS18-09	SUS 303
1.4301	X2CrNi19-11 X2CrNi18-10	304	S30400	X5CrNi18-9 X5CrNi18-10 XCrNi19-9	304S 15 304S 16 304S 18 304S 25 En58E	X5CrNi18-10	SUS 304 SUS 304-CSP
1.4306	X2CrNi19-11	304L	S30403		304S 11		SUS304L
1.4311	X2CrNiN18-10	304LN	S30453
1.4948	X6CrNi18-11	304H	S30409
1.4303	X5CrNi18-12	305	S30500
1.4401 1.4436	X5CrNiMo17-12-2 X5CrNiMo18-14-3	316	S31600	X5CrNiMo17 12 2 X5CrNiMo17 13 3 X5CrNiMo 19 11 X5CrNiMo 18 11	316S 29 316S 31 316S 33 En58J	X5CrNiMo17 12 X5CrNiMo17 13 X8CrNiMo17 13	SUS 316 SUS316TP
1.4404	X2CrNiMo17-12-2	316L	S31603		316S 11		SUS316L
1.4406 1.4429	X2CrNiMoN17-12-2 X2CrNiMoN17-13-3	316LN	S31653
1.4571		316Ti	S31635	X6CrNiMoTi17-12	320S 33
1.4438	X2CrNiMo18-15-4	317L	S31703
1.4541		321	S32100	X6CrNiTi18-10	321S 31		SUS321
1.4878	X12CrNiTi18-9	321H	S32109
1.4512	X6CrTi12	409	S40900
		410	S41000
1.4016		430	S43000	X6Cr17	430S 17		SUS430
		440A	S44002
1.4112		440B	S44003
1.4125		440C	S44004
1.4104		440F	S44020	X14CrMoS17			SUS430F
1.4539	X1NiCrMoCu25-20-5	904L	N08904
1.4547	X1CrNiMoCuN20-18-7		S31254
Tool steels
1.2363	X100CrMoV5	A-2		X100CrMoV51	BA 2	X100CrMoV5-1 KU	SKD 12
1.2379	X153CrMoV12	D-2		X153CrMoV12-1	BD 2	X155CrVMo12-1	SKD 11
1.2510		O-1		100MnCrW4	Bo 1	95MnWCr-5 KU

Remember to note that steel equivalent grades may have slight variations in chemistry between specifications. These are simply the closed grades commonly available in difference national / international specifications.

July 24, 2010December 9, 2017

AISI / SAE STEEL NUMBERING SYSTEM

The AISI / SAE Steel numbering system has some logic to it that will help you identify some key points right away even if you are not familiar with a particular grade.

The first two numbers indicate the alloy according the the chart below.
The last two numbers indicate the amount of carbon in the alloy, where the digits “10”, for example, represent 0.10% carbon.

Example AISI/SAE 1020

the first two digits indicate this is plain carbon steel.
the last two digits indicates that the steel contains approximately 0.20% carbon.

Example AISI/SAE 4340

the first two digits indicate this is a Nickel-Chromium-Molybdenum alloy steel
the last two digits indicate that the steel contains approximately 0.4% carbon

AISI/SAE Steel Numbering System

Carbon steels	10XX	Plain carbon, Mn 1.00% max
	11XX	Resulfurized free machining
	12XX	Resulfurized/rephosphorized free machining
	15XX	Plain carbon, Mn 1.00-1.65%
Manganese steel	13XX	Mn 1.75%
Nickel steels	23XX	Ni 3.50%
Nickel steels	25XX	Ni 5.00%
Nickel-chromium steels	31XX	Ni 1.25%, Cr .65-.80%
	32XX	Ni 1.75%, Cr 1.07%
	33XX	Ni 3.50%, Cr 1.50-1.57%
	34XX	Ni 3.00%, Cr .77%
Molybdenum steels	40XX	Mo .20-.25%
Molybdenum steels	44XX	Mo .40-.52%
Chromium-molybdenum steels	41XX	Cr .50-.95%, Mo .12-.30%
Nickel-chromium-molybdenum steels	43XX	Ni 1.82%, Cr .50-.80%, Mo .25%
Nickel-chromium-molybdenum steels	47XX	Ni 1.05%, Cr .45%, Mo .20-.35%
Nickel-molybdenum steels	46XX	Ni .85-1.82%, Mo .20-.25%
Nickel-molybdenum steels	48XX	Ni 3.50%, Mo .25%
Chromium steels	50XX	Cr .27-.65%
	51XX	Cr .80-1.05%
	50XXX	Cr .50%, C 1.00% min
	51XXX	Cr 1.02%, C 1.00% min
	52XXX	Cr 1.45%, C 1.00% min
Chromium-vanadium steels	61XX	Cr .60-.95%, V .10-.15%
Tungsten-chromium steels	72XX	W 1.75%, Cr .75%
Nickel-chromium-molybdenum steels	81XX	Ni .30%, Cr .40%, Mo .12%
	86XX	Ni .55%, Cr .50%, Mo .20%
	87XX	Ni .55%, Cr .50%, Mo .25%
	88XX	Ni .55%, Cr .50%, Mo .35%
Silicon-manganese steels	92XX	Si 1.40-2.00%, Mn .65-.85%, Cr 0-.65%
Nickel-chromium-molybdenum steels	93XX	Ni 3.25%, Cr 1.20%, Mo .12%
	94XX	Ni .45%, Cr .40%, Mo .12%
	97XX	Ni .55%, Cr .20%, Mo .20%
	98XX	Ni 1.00%, Cr .80%, Mo .25%

July 23, 2010December 9, 2017

Sheet Metal Gauge Chart – Steel, Stainless, Aluminum, Tubing

Damn you, sheet metal gods! Why did you create such a stupid system where a “gauge” of one type of metal is a different thickness than the same “gauge” of another metal? The sheet metal gauge chart will help you with your struggle to pick a ‘standard’ size sheet metal whey you are working on a sheet metal design.

All Dimensions in Inches

Gauge #	Sheet Steel	Strip & Tubing	Aluminum	Stainless Steel
6/0 5/0 4/0 3/0 2/0	—- —- —- —- —-	—- .500 .454 .425 .380	.5800 .5165 .4600 .4096 .3648	.4687 .4375 .4062 .3750 .3437
0 1 2 3 4 5	—- —- —- .2391 .2242 .2092	.340 .300 .284 .259 .238 .220	.3249 .2893 .2576 .2294 .2043 .1819	.3125 .2812 .2656 .2500 .2344 .2187
6 7 8 9 10 11	.1943 .1793 .1644 .1495 .1345 .1196	.203 .180 .165 .148 .134 .120	.1620 .1443 .1285 .1144 .1019 .0907	.2031 .1875 .1719 .1562 .1406 .1250
12 13 14 15 16 17	.1046 .0897 .0747 .0673 .0598 .0538	.109 .095 .083 .072 .065 .058	.0808 .0720 .0641 .0571 .0508 .0453	.1094 .0937 .0781 .0703 .0625 .0562
18 19 20 21 22 23	.0478 .0418 .0359 .0329 .0299 .0269	.049 .042 .035 .032 .028 .025	.0403 .0359 .0320 .0285 .0253 .0226	.0500 .0437 .0375 .0344 .0312 .0281
24 25 26 27 28 29	.0239 .0209 .0179 .0164 .0149 .0135	.022 .020 .018 .016 .014 .013	.0201 .0179 .0159 .0142 .0126 .0113	.0250 .0219 .0187 .0172 .0156 .0141
30 31 32 33 34 35 36 37 38	.0120 .0105 .0097 .0090 .0082 .0075 .0067 .0064 .0060	.012 .010 .009 .008 .007 .005 .004 —- —-	.0100 .0089 .0080 .0071 .0063 .0056 .0050 .0045 .0040	.0125 .0109 .0102 .0094 .0086 .0078 .0070 .0066 .0062

Remember, mechanical engineers, if you ever serve on a standards or specifications committee, don’t make up stupid rules and specifications just to be different. Try to make things common so you don’t need extra tools like this sheet metal gauge chart which should be totally unnecessary.