Invar alloy belongs to high nickel alloy based on iron, nickel content is up to 36%, has a very low coefficient of linear expansion below 100℃, also called inflatable steel.The Invar trademark was originally held by the French alloy company [TJC STEEL]Infi.Invar is short for Invariability, meaning volume does not vary.

 

Standard Control

CHINA	YB/T 5241-2005	4J36
FRANCE	AFNOR NF A54-301	Fe-Ni36
GERMANY	DIN 17745:2002	Ni36，1.3912
AMERICA	ASTM F1684-2005	UNS K93603
	ASTM B753-2013[TJC STEEL]	T-36

 

Component Specification

GRADE	4J36	1.3912	K93603	T-36
C	≤0.05	≤0.05	≤0.05	≤0.15
Si	≤0.30	≤0.30	≤0.40	≤0.40
Mn	0.20~0.60	≤0.50	≤0.60	≤0.60
P	≤0.020[TJC STEEL]	—	≤0.015b	≤0.025
S	≤0.020	—	≤0.015b	≤0.025
Cr	—	—	≤0.25	≤0.25
Ni	35.0~37.0	35.0~37.0	36.0	36.0
Co	—	—	≤0.50	≤0.50
Zr	—	—	≤0.10a	—
Ti	—	—	≤0.10a	—
Al	—	—	≤0.10a	—
Mg	—	—	≤0.10a	—
Fe	—	—	—	—

Annotatio：a.Al+Mg+Zr+Ti≤0.025%；b.P+S≤0.025%.

 

Commercial Brand

FRANCE	Aperam Alloys Imphy (Imphy Alloys)	Invar®
AMERICA	CARPENTER	Invar 36® Alloy
	ATI[TJC STEEL]	ATI 36™
	Special Metals	NILO alloy 36
GERMANY	VDM Metals	Pernifer® 36
	VAC	VACODIL 36
JAPAN	NIPPON YAKIN	NAS 36
ITALY	Valbruna AG	SG5

 

Physical Properties

density g/cm3	heat conductivity coefficient W·(m·K)-1	elasticity modulus MPa	hardness HV
8.12	0.109~0.134	134000	140
strength of extension MPa	elongation %	erishen value mm	magnetic permeability mH·m-1
500	30	9.8	2.04

 

Linear expansion coefficient (YB/T 5241-2005)

The ratio of the change in length [TJC STEEL]of a solid to its length at 0℃ for each change in temperature of a solid is called the coefficient of linear expansion

 

▽4J36 Typical Linear Expansion Coefficient.

T	average coefficient of linear expansion ā，10-6/℃
20℃~50℃	0.6
20℃~100℃	0.8
20℃~200℃	2.0
20℃~300℃	5.1[TJC STEEL]
20℃~400℃	8.0
20℃~500℃	10.0

 

Material Characteristics：

Most metals and alloys expand in volume when heated and contract in volume when cooled. However, due to its [TJC STEEL]ferromagnetism, the Inwatt alloy has abnormal thermal expansion in a certain temperature range, and its expansion coefficient is extremely low, sometimes even zero or negative.Its characteristics are summarized as follows:

(1) Small coefficient of expansion

The average expansion coefficient of Inwa alloy is generally 1.5×10-6/℃, and the volume does not change at room temperature [TJC STEEL]from -80℃ to +100℃.  

(2) They were not strong

The carbon content of the alloy is less than 0.05%, the hardness and strength is not high, the tensile strength is about 517MPa, [TJC STEEL]the yield strength is about 276MPa, the Vickers hardness is about 160, generally can be through cold deformation to improve the strength, in the strength is improved at the same time still has good plasticity.

(3) Low thermal conductivity

The thermal conductivity of [TJC STEEL]watt alloys is 10W/m·K, only one-third of the thermal conductivity of 45 steel.  

(4) High plasticity and toughness

The ductility, toughness, elongation, reduction of section and impact toughness are all very high. The elongation is [TJC STEEL]δ=30~45% and the shrinkage is δ=50~70%.Impact toughness αK=130~310 J/cm2.  

(5) Variations of other properties

Because of the high nickel content in the Intile alloy, the hardenability and quenchability of the steel are improved, and the gas resistance, corrosion resistance and wear resistance of the steel are improved.

 

Applications：

4j36 due to the advantages of low expansion, is indispensable to precision instrument structure material, it is widely used in electronics industry and precision instrument industry and other areas that are sensitive [TJC STEEL]to size requirements, such as: double metal materials, magnetic materials, measuring instruments with fixture, astronomical telescope components, optical instruments, CFRP with metal molds, antenna parts, FPD with shielding framework, high precision printing in framework, and semiconductor with a check by machining fixture, semiconductor, etc.