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VDM® Alloy 36

Alternative and trade names
Pernifer 36, Invar® 36


Pernifer 36 is an austenitic binary iron-nickel alloy with a particularly low coefficient of expansion. Control of carbon and manganese contents as well as impurities is important. It is ferromagnetic at temperatures below the Curie temperature and non-magnetic at temperatures above. Cold deformation reduces the thermal expansion. A 3-step ageing treatment stabilizes the coefficient of expansion within a selected temperature range.

Pernifer 36 is characterized by:

  • Extremely low coefficient of thermal expansion between -250 and +200°C
  • Good ductility and toughness
  • Good fatigue and mechanical properties at cryogenic temperature

Related Standards

Equivalent Materials



Electrical resistivity ρel

7.6E-7 Ω·m at 20 °C

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Density ρ

8.1 g/cm³ at 20 °C


Curie temperature Tc

280 °C at 20 °C


Elastic modulus E

133 GPa at -250 °C

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Elongation A5 A5

40 % at -250 °C

Typical mechanical properties in the soft-annealed condition

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Impact strength, Charpy notched Ivnot

1320 kJ/m² at 20 °C

Tensile strength Rm

1000 MPa at -250 °C

Typical mechanical properties in the soft-annealed condition

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Yield strength Rp0.2 Rp0.2

880 MPa at -250 °C

Typical mechanical properties in the soft-annealed condition

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Coefficient of thermal expansion α

1.3E-6 - 2.2E-6 1/K at -250 °C

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Melting point Tm

1430 °C

Specific heat capacity cp

515 J/(kg·K) at 20 °C

Thermal conductivity λ

2 W/(m·K) at -250 °C

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Chemical properties


Weight %






35 - 37 %


0.6 %



0.5 %



0.4 %



Technological properties

Application areas

Sulphuric acid production plant, sulphuric acid heat recovery and distribution systems, nitric-hydrofluoric acid pickling plant, seawater systems, plate or tubular heat exchangers using brackish or seawater as coolant, bleaching plant for chemical pulp.

Corrosion properties

Pernifer 36 is corrosion resistant in dry atmospheres at room temperature. Under unfavourable conditions, i.e., in humid or moist atmospheres, corrosion can occur in the form of rust.

General machinability

Pernifer is tough and ductile and therefore somewhat difficult to machine. It should be machined in the annealed condition. The machining characteristics of Pernifer 36 are similar to austenitic stainless steels. Because of its high ductility, the chips formed during machining tend to be stringy and tough and may thus impose rapid wear on the cutting tool edges. In general, slow speeds and light feeds should be used to avoid excessive heat and minimize the possibility of the generated heat affecting the expansion characteristics. An adequate depth of cut is important, however, in order to cut below any previously formed work-hardened zone. High speed steel or sintered carbide tools should be used and cutting edges should be kept sharp.


In the annealed condition Pernifer 36 exhibits an austenitic structure.

This material data has been provided by VDM Metals.

All metrics apply to room temperature unless otherwise stated. SI units used unless otherwise stated.
Equivalent standards are similar to one or more standards provided by the supplier. Some equivalent standards may be stricter whereas others may be outside the bounds of the original standard.