List of Alloys & profiles

List of Alloys & profiles

Alloy Wire International

Datasheet: Heatseal 29

Heatseal 29

Heatseal 29 is a Nickel-Iron-Cobalt alloy that has a controlled expansion coefficient. Its expansion with temperature rise is less than that of 80/20 NiCr.

Available in all profile options

Heatseal 29 - Alloy Wire International 1

Key Features

Heatseal 29 offers the following key features:

Having low expansion as it’s temperature increases makes it an ideal heating element wire for heat sealing (plastic bag welding) over a long straight length.

Typical Applications

Heatseal 29 is known to be suitable for the following applications:

Heat sealing (plastic bag welding) long lengths of plastic bags where low expansion of the wire is important to ensure straightness of the weld.

Examples include heat sealing plastic bags for bed mattresses.


AWS 094

Chemical Composition

The chemical composition of Heatseal 29 is indicated in the table below:

ElementMin %Max %
Fe53.00 nominal
Ni29.00 nominal
Co17.00 nominal

Alloy Details

Heatseal 29 density, melting point, inflection point, thermal conductivity, and coefficient of expansion is indicated in the table below:

DensityMelting PointInflection PointThermal ConductivityCoefficient of Expansion
8.16 g/cm³1450 °C450 °C16.7 W/m• °C6.0 µm/m °C (20 – 100 °C)
4.6 – 5.2 µm/m °C (20 – 400 °C)
0.295 lb/in³2640 °F840 °F116 btu•in/ft2•h °F3.3 x 10-6 in/in °F (70 – 212 °F)
2.6 – 2.9 x 10-6 in/in °F (70 – 752 °F)

Heat treatment of finished parts

The typical heat treatment of Heatseal 29:

Condition as supplied by Alloy WireTypeTemperatureTimeCooling
Anneal850 – 1000 °C (1560 – 1830 °F)0.5 HrAir or water
To prepare for glass to metal sealingDecarburization900 – 1050 °C (1650 – 1920 °F)1 HrAir or water
If a metal oxide interface is required
(time and temperature depend on required oxide thickness)
Oxidize600 – 1000 °C (1110 – 1830 °F)1 HrAir

Heatseal 29 is usually supplied and used in the annealed condition (residual cold work distorts the coefficients of thermal expansion.) Annealing times may vary due to section thickness. Oxidising time and temperature to be selected depending on required oxide thickness.


The typical mechanical properties of Heatseal 29:

Approx. tensile strength<550 N/mm²<80 ksi
Approx. operating temperatureup to +400 °Cup to +750 °F
Hard Drawn
Approx. tensile strength700 – 900 N/mm²102 – 131 ksi
Approx. operating temperatureup to +400 °Cup to +750 °F

The above tensile strength ranges are typical. If you require different please ask.