Low Expansion Alloys Invar36 Nilo 36 Wire

Product Description

Invar36 Nilo 36 Wire Low Expansion Alloys

(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(OMmm^2/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	In protective media and heated to 830 ºC, hold 20min. ~ 1h, quench Due to the stress generated by quenching, heated to 315ºC,hold 1~4h.
Precautions	Can not be hardened by heat treatment Surface treatment can be sandblasting, polishing or pickling. 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/ 10^3 *ºC	1.8	1.7	1.4	1.2	1.0