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6J40 Constantan Copper-Nickel Alloy Optimal Choice For Stable Electrical Properties

6J40 Constantan Copper-Nickel Alloy Optimal Choice For Stable Electrical Properties

A constant alloy is a type of metal alloy designed to maintain stable and consistent properties, particularly electrical resistance, over a wide range of temperatures. The most well-known constant alloy is Constantan, a copper-nickel alloy that is widely used in temperature sensors (thermocouples), resistors, and heating elements due to its stable electrical and thermal characteristics.

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6J40 Constantan Copper-Nickel Alloy The Optimal Choice for Stable Electrical Properties

Constant alloys, like 6J40, are valued for their reliable and consistent performance in a wide range of applications. Their ability to maintain stable electrical resistance and durability under varying environmental conditions makes them essential in industries like electronics, manufacturing, and scientific instrumentation.

Chemical composition

Name	Code	Main Composition(%)				Density
Name	Code	Cu	Mn	Ni	Cr	g/mm2
Constantan	6J40	Bal.	1~2	39~41	--	8.9

Properties

Name	Code	Resistivity(20℃)(μΩm)	Temp.Coeff.Of Resistance (20℃)(α×10-6/℃)	(0~100℃) Thermal EMF vs. Copper (μv/℃)	Max. Working Temp. (℃)	Elongation(%)	Tensile Strength(N/mm2)
Constantan	6J40	0.48±0.03	-40~+40	45	≤500	≥15	≥390

Diameter and Tolerance

Diameter	0.02~0.028	0.032~0.10	0.112~0.28	0.315~0.50	0.56~1.0	1.06~1.60	1.70~2.12	2.24~3.00	3.15~4.50
Tolerance	±0.002	±0.003	±0.005	±0.010	±0.015	±0.020	±0.025	±0.030	±0.035

Some key features of 6J40 include:

Stable Electrical Resistance:

Constantan (commonly an alloy of 55% copper and 45% nickel) maintains constant electrical resistance across a wide range of temperatures. This property makes it particularly useful in applications requiring precise and stable resistance, such as in thermocouples (temperature sensors) and resistors.

2. Low Temperature Coefficient of Resistance:

The alloy's resistance does not change much with temperature fluctuations. This low temperature coefficient ensures that devices made from constant alloys will maintain stable performance even in environments with varying temperatures.

3. Good Corrosion Resistance:

Constant alloys, especially Constantan, have good corrosion resistance, making them durable for long-term use in harsh environments. This is essential in outdoor and industrial applications where exposure to moisture, chemicals, or high humidity is common.

4. Thermoelectric Properties:

Due to its stable electrical resistance, Constantan is widely used in thermocouples to measure temperature. The difference in voltage generated by two different metals (like Constantan and another metal) when exposed to heat is used in these sensors to provide accurate temperature readings.

Thermoelectric Seebeck Coefficient: Constantan has a good Seebeck coefficient, which means it can generate a voltage that is proportional to the temperature difference across the metal, making it ideal for temperature measurement.

5. Durability and Strength:

Constant alloys are relatively strong and resistant to mechanical wear. Their tensile strength and mechanical stability make them useful in applications that require durability, such as in electrical cables, resistance wire, and heating elements.

6. Formability and Ductility:

Constant alloys are generally ductile and can be easily drawn into thin wires or formed into various shapes without losing their properties. This makes them versatile for use in a wide variety of applications, from precision resistors to wire-wound heating elements.

7. High Melting Point:

Constant alloys typically have high melting points, allowing them to withstand high temperatures without degradation. This property is especially useful in heating elements (like those in ovens, toasters, and industrial furnaces) that require stable performance under heat stress.

8. Magnetic Properties:

Constantan and similar alloys typically have non-magnetic properties, which makes them useful in applications where magnetic interference needs to be avoided, such as in sensitive electronic equipment or instrumentation.

Applications:

Thermocouples: Constant alloys are commonly used in temperature measurement devices due to their stable resistance.

Electrical Resistance: Used in resistors, shunt resistors, and strain gauges due to their predictable and stable resistance characteristics.

Heating Elements: Used in high-temperature resistance wires for electric heating applications.

Sensors and Instrumentation: Due to their stable resistance, constant alloys are used in pressure sensors, strain gauges, and other precision instruments.

Constantan (6J40) Technical data of wires

Dia(m)	Cross-sectional area(m²)	Weight/m (g/m)	Resistance/m at 20℃(Ω/m)	Dia(m)	Cross-sectional area(m²)	Weight/m (g/m)	Resistance/m at 20℃(Ω/m)
0.020	0.000314	0.00279	1375-1681	0.224	0.03941	0.350	11.4-12.9
0.022	0.000318	0.00337	1136-1389	0.250	0.04909	0.436	9.19-10.37
0.025	0.000491	0.00434	880-1076	0.280	0.06158	0.5468	7.33-8.26
0.028	0.000616	0.00547	702-857	0.315	0.07793	0.6920	5.85-6.47
0.032	0.000804	0.00714	549-645	0.355	0.09898	0.8789	4.61-5.09
0.036	0.001018	0.00904	434-509	0.400	0.12570	1.116	3.63-4.01
0.040	0.001257	0.01116	351-413	0.450	0.15900	1.412	2.87-3.17
0.045	0.001509	0.01412	278-326	0.500	0.19630	1.744	2.32-2.57
0.050	0.001963	0.01744	225-264	0.560	0.24630	2.19	1.87-2.03
0.056	0.002463	0.02187	179-210	0.630	0.31170	2.77	1.48-1.60
0.063	0.003117	0.02768	142-166	0.710	0.39590	3.52	1.16-1.26
0.071	0.003959	0.03516	112-131	0.750	0.44180	3.92	1.04-1.13
0.080	0.005027	0.04464	87.9-103.1	0.800	0.50270	4.46	0.917-0.993
0.090	0.006362	0.05650	69.4-81.5	0.850	0.56740	5.04	0.812-0.880
0.100	0.007854	0.06970	56.2-66.0	0.900	0.63620	5.65	0.724-0.785
0.112	0.009852	0.08749	45.3-52.1	0.950	0.70880	6.29	0.650-0.704
0.125	0.012270	0.10900	36.4-41.9	1.000	0.78540	6.97	0.587-0.636
0.140	0.015390	0.13670	29.0-33.4	1.060	0.88250	7.84	0.522-0.566
0.150	0.017670	0.15690	25.3-29.1	1.120	0.98520	8.75	0.468-0.507
0.160	0.020110	0.17850	22.2-25.5	1.180	1.09400	9.71	0.421-0.456
0.170	0.022700	0.20160	19.7-22.6	1.250	1.22700	10.9	0.375-0.407
0.180	0.025450	0.22600	17.5-20.2	1.320	1.36800	12.15	0.337-0.365
0.190	0.028350	0.25200	15.7-18.1	1.400	1.53900	13.67	0.299-0.324
0.200	0.031420	0.27900	14.4-16.2	1.500	1.76700	15.69	0.261-0.282
0.212	0.035300	0.31350	12.8-14.4	1.600	2.01100	17.86	0.229-0.248

Constantan strip resistance value (Ω/m)

Width Thickness	6.3	8.0	10.0	12.5	16.0	20.0	25.0	31.5	40.0
0.180	0.150
0.200	0.405
0.224	0.362	0.2850
0.250	0.324	0.2550	0.196
0.280	0.289	0.2280	0.175
0.315	0.257	0.2030	0.155	0.124
0.355	0.228	0.1800	0.138	0.110
0.400	0.203	0.1600	0.122	0.980	0.0765
0.450	0.180	0.1420	0.109	0.0871	0.0680	0.0544	0.0435
0.500	0.162	0.1280	0.098	0.0784	0.0612	0.0490	0.0392
0.560	0.145	0.1140	0.0875	0.0700	0.0547	0.0437	0.0350
0.630	0.129	0.1010	0.0777	0.0622	0.0486	0.0389	0.0311
0.710	0.114	0.0900	0.0690	0.0552	0.0431	0.0345	0.0276
0.800	0.101	0.0800	0.0612	0.0490	0.0383	0.0306	0.0245	0.0194	0.0153
0.900	0.090	0.0710	0.0544	0.0435	0.0340	0.0272	0.0218	0.0173	0.0136
1.000	0.081	0.0640	0.0490	0.0392	0.0306	0.0245	0.0196	0.0155	0.0122
1.120	0.072	0.0570	0.0437	0.0350	0.0273	0.0219	0.0175	0.0139	0.0109
1.250	0.065	0.0510	0.0392	0.0313	0.0245	0.0196	0.0157	0.0124	0.0098
1.400	0.058	0.0460	0.0350	0.0280	0.0219	0.0175	0.0140	0.0111	0.0088
1.600	0.051	0.0400	0.0306	0.0245	0.0191	0.0153	0.0122	0.0097	0.0077
1.800	0.045	0.0350	0.0272	0.0218	0.0170	0.0136	0.0109	0.0086	0.00680
2.000	0.041	0.0320	0.0245	0.0196	0.0153	0.0122	0.0098	0.0078	0.0061

Constantan&Manganin wire table

Dia.(mm)		Sectional area nominal value(mm2)	Resistance per meter (Ω/m)
Dia.(mm)			6J12X		6J8X		6J13X		6J40X
Nominal value(mm)	Tolerance		Nominal value (Ω/m)	Tolerance	Nominal value (Ω/m)	Tolerance	Nominal value (Ω/m)	Tolerance	Nominal value (Ω/m)	Tolerance
0.020	±0.002	0.000314	1496	±10%					1528	±10%
0.022		0.000380	1236						1263
0.025		0.000491	957						978
0.028		0.000616	763						780
0.032	±0.003	0.000804	584	±8%		±8%		±8%	597	±8%
0.036		0.001018	462						472
0.040		0.001257	374						382
0.045		0.001590	296						302
0.050		0.001963	239						244
0.056		0.002463	191						195
0.063		0.003117	151						154
0.071		0.003959	119						121
0.080		0.005027	93.5		69.6		87.5		95.5
0.090		0.006362	73.9		55.0		69.2		75.5
0.100		0.007854	59.8		44.6		56.0		61.1
0.112	±0.005	0.009852	47.7	±7%	35.5	±7%	44.7	±7%	48.7	±7%
0.125		0.01227	38.3		28.5		35.9		39.1
0.140		0.01539	30.5		22.7		28.6		31.2
0.160		0.02011	23.4		17.4		21.9		23.9
0.180		0.02545	18.5		13.8		17.3		18.9
0.200	±0.005	0.03142	15.0	±6%	11.1	±6%	14.0	±6%	15.3	±6%
0.224		0.03941	11.9		8.88		11.2		12.2
0.250		0.04909	9.57		7.13		8.96		9.78
0.280		0.06158	7.63		5.68		7.15		7.80
0.315	±0.010	0.007793	6.03	±5%	4.49	±5%	5.65	±5%	6.16	±5%
0.355		0.09898	4.75		3.54		4.45		4.85
0.400		0.1257	3.74		2.79		3.50		3.82
0.450		0.1590	2.96		2.20		2.77		3.02
0.500	±0.015	0.1963	2.39	±4%	1.78	±4%	2.24	±4%	2.44	±4%
0.560		0.2463	1.91		1.42		1.79		1.95
0.630		0.3117	1.51		1.12		1.41		1.51
0.710		0.3959	1.19		0.884		1.11		1.21
0.750		0.4418	1.06		0.792		1.00		1.09
0.800		0.5027	0.935		0.696		0.875		0.955
0.850		0.5674	0.828		0.617		0.775		0.846
0.900		0.6362	0.739		0.550		0.692		0.755
0.950		0.7088	0.663		0.494		0.621		0.677
1.000		0.7854	0.598		0.446		0.560		0.611
1.060	±0.020	0.8852	0.533	±4%	0.397	±4%	0.499	±4%	0.544	±4%
1.120		0.9852	0.477		0.355		0.447		0.487
1.180		1.094	0.430		0.320		0.402		0.439
1.250		1.227	0.383		0.285		0.359		0.391
1.320		1.368	0.343		0.256		0.322		0.351
1.400		1.539	0.305		0.227		0.286		0.312
1.500		1.767	0.266		0.198		0.249		0.272
1.600		2.011	0.234		0.174		0.219		0.239
1.700	±0.025	2.270	0.207	±4%	0.154	±4%	0.194	±4%	0.211	±4%
1.800		2.545	0.185		0.138		0.173		0.189
1.900		2.835	0.166		0.123		0.155		0.169
2.000		3.142	0.15		0.111		0.140		0.153
2.120		3.530	0.133		0.0992		0.125		0.136
2.240	±0.030	3.941	0.119	±4%	0.0888	±4%	0.112	±4%	0.122	±4%
2.360		4.374	0.107		0.0800		0.101		0.110
2.500		4.909	0.0957		0.0713		0.0896		0.0978
2.650		5.515	0.0852		0.0635		0.0798		0.0870
2.800		6.158	0.0763		0.0568		0.0715		0.0780
3.000		7.069	0.0665		0.0495		0.0622		0.0679
3.150	±0.035	7.793	0.0603	±4%	0.0449	±4%	0.0565	±4%	0.0616	±4%
3.350		8.814	0.0533		0.0397		0.0499		0.0545
3.550		9.898	0.0475		0.0354		0.0445		0.0485
3.750		11.04	0.0426		0.0317		0.0398		0.0435
4.000		12.57	0.0374		0.0279		0.0350		0.0382
4.250		14.19	0.0331		0.0247		0.0310		0.0338
4.500		15.90	0.0296		0.0220		0.0277		0.0302
4.750	±0.040	17.72	0.0265	±4%	0.0198	±4%	0.0248	±4%	0.0271	±4%
5.000	±0.040	19.63	0.0239	±4%	0.0178	±4%	0.0224	±4%	0.0244	±4%
5.300	±0.050	22.06	0.0213	±4%	0.0159	±4%	0.0199	±4%	0.0218	±4%
5.600	±0.050	24.63	0.0191	±4%	0.0142	±4%	0.0179	±4%	0.0195	±4%
6.000	±0.060	28.27	0.0166	±4%	0.0124	±4%	0.0156	±4%	0.017	±4%
6.300	±0.060	31.17	0.0151	±4%	0.0112	±4%	0.0141	±4%	0.0154	±4%

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