Physical characteristics of Nimonic 75 resistance wire

Nimonic 75 Resistance Wire

The Nimonic 75 resistance wire is basically nickel chromium 80 – 20 alloy cable with the restricted addition of titanium and carbon. The wire was first time made for making the turbine cutting-edges in the prototype whittle jet motors. It is furthermore used for jobs of oxidation and scalling opposition paired with intermediate potency at the large warmth applications.

Today the cable is also utilized in the gas turbines procedures and commercial thermal treatment, furnace components and heat processing apparatus. It is effortlessly formed and welded. The underneath table displays the chemical composition of nimonic 75 resistance wire:

Carbon 0.08-0.15 %
Chromium 18.0-21.0 %
Copper 0.5 %
Iron 5.0 %
Manganese 1.0 %
Silicon 1.0 %
Titanium 0.2-0.6 %
Nickel Bal.

The physical features of nimonic 75 alloy wire are shown below:

Density 8.37 Mg/m3
Melting Range 1340-1380oC or 2450-2520oF
Specific Heat 461 J/kg•°C at 20°C
Thermal Conductivity 11.7 W/m•°C at 20°C
Electrical Resistivity 1.09 µΩ•m at 20°C

The mean coefficient of thermal expansion properties of alloy are shown below:

oC 10-6/oC
20-100 11.0
-200 12.7
-300 13.4
-400 13.9
-500 14.3

The dynamic young modulus of nimonic 75 alloy is supplied in the below table:

oC oF Gpa
20 68 221
100 212 216
200 392 210
300 572 203
400 752 197

To perform check, the alloy specimen is heat processed for half to one hour at temperature of 1050oC or 1920oF and air quenched and sheet alloy is heat processed for 5 to 10 minutes at temperature of 1050oC or 1920oF and air quenched.

The opposition to oxidation characteristics of nimonic 75 resistance wire are contrasted with other nimonic alloys in the underneath table:

Alloy Weight Loss (mg/cm2) after 100 hours at
800oC (1470°F) 900oC(1650oF) 950oC(1740oF) 1000oC(1830oF 1100oC(2010oF)
Nimonic 75 0.55 1.18 4.00 6.66 8.92
Nimonic 80A 0.64 2.62 3.96 5.96 11.20
Nimonic 90 0.46 2.52 5.50 10.40 11.23
Nimonic 105 0.11 0.49 0.99 1.43 6.49

To make the continuous heating system investigation, the material is oxidized in the air and decrease of weight is calculated after the descaling electrolysis in sodium hydroxide.

The Nimonic 75 resistance wire offers steady, austenitic and solid solution properties at the distinct warmth lower than the solidification and omitted from the recrystallization and kernel development is isolated by the heat processing. Generally the three phases are shown: oxide or silicate added that are initiated from the deoxidation of the molten steel present in the polished condition in the pattern of little, gloomy inclusion rapidly accessible as stringers in the rudimentary processing direction.

The intergranularly happens in the rudimentary carbide, nitride or carbonitride. These are shown in the polished status as substantially equiazxed, fundamentally spherical or cuboid which color changes from the white to purple in case of carbide to yellow for the nitride. The chromium grain limit carbides, these dissolve in the matrix to heat though at a warmth much bigger than the normal annealing warmth.

The effective scrapes for the nimonic 75 resistance wire are 4% aqueous solution of sulfuric acid utilized electrolytically at promise distinction of 4V and the fry reagent.


Isha Changotra has wide experience in metals industry and is working for a renowned super alloys manufacturer located in China and United States. With extensive insight in metals and high performance super alloys, she aims to provide most useful information for folks engaged under this niche.

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