Nickel - Iron Alloy Bellows Materials - Bellows Systems

Invar 36 (UNS: K93600)

Bellows Materials Invar 36
Description A nickel-iron, low-expansion alloy containing 36% nickel. It maintains nearly constant dimensions over the range of normal atmospheric temperatures, and has a low coefficient of expansion from cryogenic temperatures to about 500°F.
Application Notes The alloy also retains good strength and toughness at cryogenic temperatures. INVAR 36 can be hot and cold formed and machined using processes similar to austenitic stainless steels.
Industry Uses /Products Cryogenic bellows, Instrument bellows, Vacuum Bellows for semiconductor industry
UNS K93600

Material Properties

Density, ρ, lbs/in^3 0.293
Yield Strength, Sy, Psi 35000
Tensile Strength, Su, Psi 42
Coeff. Thermal Expansion, in/in/˚F 0.0000008
Melting Point, ˚F 2605

Post Weld Heat Treatement (PWHT)

Stress Relive 2 hrs at 600F air or oven cool
Annealing 1 hr at 1550F after forming and /or welding