Model NO.: invar
Material: Fe- Ni Alloy
Surface: Smooth and Bright
Condition: Soft
Trademark: TANKII
Transport Package: Wooden Case
Specification: 1.5x200
Origin: Shanghai, China
HS Code: 7505120000

Good Quality Iron Nickel Alloy Invar 36


(Common Name: Invar, FeNi36, Invar Standard, Vacodil36)

4J36 (Invar), also known generically as FeNi36 (64FeNi in the US), is a nickel-iron alloy notable for its uniquely low coefficient of thermal expansion (CTE or α).

4J36 (Invar) is used where high dimensional stability is required, such as precision instruments, clocks, seismic creep gauges, television shadow-mask frames, valves in motors, and antimagnetic watches. In land surveying, when first-order (high-precision) elevation leveling is to be performed, the Level staff (leveling rod) used is made of Invar, instead of wood, fiberglass, or other metals. Invar struts were used in some pistons to limit their thermal expansion inside their cylinders.

4J36 use oxyacetylene welding, electric arc welding, welding and other welding methods. Since the coefficient of expansion and chemical composition of the alloy is related should be avoided due to welding causes a change in the alloy composition, it is preferable to use Argon arc welding welding filler metals preferably contains 0.5% to 1.5% titanium, in order to reduce weld porosity and crack.

Normal composition%

Ni 35~37.0 Fe Bal. Co - Si ≤0.3
Mo - Cu - Cr - Mn 0.2~0.6
C ≤0.05 P ≤0.02 S ≤0.02    

Coefficient of expansion

θ/ºC α1/10-6ºC-1 θ/ºC α1/10-6ºC-1
20~-60 1.8 20~250 3.6
20~-40 1.8 20~300 5.2
20~-20 1.6 20~350 6.5
20~-0 1.6 20~400 7.8
20~50 1.1 20~450 8.9
20~100 1.4 20~500 9.7
20~150 1.9 20~550 10.4
20~200 2.5 20~600 11.0

 

Typical Physical properties

Density (g/cm3) 8.1
Electrical resistivity at 20ºC(OMmm2/m) 0.78
Temperature factor of resistivity(20ºC~200ºC)X10-6/ºC 3.7~3.9
Thermal conductivity, λ/ W/(m*ºC) 11
Curie point Tc/ ºC 230
Elastic Modulus, E/ Gpa 144

 

The heat treatment process
Annealing for stress relief Heated to 530~550ºC and hold 1~2 h. Cold down
annealing In order to eliminate hardening, which be bring out in cold-rolled, cold drawing process. Annealing needs heated to 830~880ºC in vacuum,hold 30 min.
The stabilization process
  1. In protective media and heated to 830 ºC, hold 20min. ~ 1h, quench
  2. Due to the stress generated by quenching, heated to 315ºC,hold 1~4h.
Precautions
  1. Can not be hardened by heat treatment
  2. Surface treatment can be sandblasting, polishing or pickling.
  3. Alloy can be used 25% hydrochloric acid pickling solution at 70 ºC to clear oxidized surface

Typical Mechanical properties

Tensile Strength Elongation
Mpa %
641 14
689 9
731 8

Temperature factor of resistivity

Temperature range, ºC 20~50 20~100 20~200 20~300 20~400
aR/ 103 *ºC 1.8 1.7 1.4 1.2 1.0

 

Good Quality Iron Nickel Alloy Invar 36



 

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