Expansion alloys
UNS Number | UNS K93600 |
Industry Name | Invar 36，FeNi36，W.Nr.1.3912 |
Product Forms | Rods, Bars, Plates, Wires, Strips |
General Characteristics
Alloy 4J36, known as Invar 36, is an iron-nickel low expansion alloy. It was developed to solve the large thermal dimensional change of common steel and non-ferrous metals at ambient temperature. Traditional metals expand or contract obviously with temperature fluctuation, which brings dimension errors for precision measuring structures.
Alloy 4J36 maintains nearly unchanged dimensions under temperature variation. It also has good ductility, easy stamping and machining, and stable dimensional performance.
C | S | P | Mn | Si | Ni | Fe |
≤0.05 | ≤0.02 | ≤0.02 | 0.2-0.6 | ≤0.3 | 35-37 | Bal. |
Aerospace & Optics||Optical mirror support frames|Laser device mounting bases|Precision sensor housings|Telescope structural components
Electronic Industry||Mask frames for semiconductor lithography|Cavity parts for microwave equipment|Precision waveguide components|Lead frames requiring stable dimension
Energy & Power||Liquid natural gas (LNG) storage and transport structural parts|Low-temperature pipeline fittings|Precision power meter internal assemblies
Technical Standard | Product Form |
YB/T 5231 | Bar, Wire, Strip, Sheet |
ASTM F1684 | Bar, Wire, Strip, Sheet, Plate |
AMS 7727 | Bar, Wire, Strip, Sheet |
Product form | Size range (mm) |
Forged bar | Dia.70-500 |
Rolled bar | Dia.2.0-70 |
Flat bar | T4-50*W60-300 |
Wire | Dia.0.25-18.0 |
Strip | 0.15-3.0 * 20-200 |
Plate | 1-25 * ≤1200 * ≤1200 |
Q1 The difference between 4J36 and 4J29?
A: 4J36 achieves ultra-low expansion around room temperature, but its thermal expansion rises rapidly above 200°C and cannot match glass for hermetic sealing. 4J29 is engineered for glass-metal sealing, while 4J36 focuses on dimensional stability for precision structures.
Q2 The difference between 4J36 and 4J42?
A: 4J42 has higher expansion coefficient than 4J36 and is used for less strict low-expansion scenarios at lower cost.
Q3: What is its effective temperature range for low expansion?
A: Best performance at -60°C ~ +80°C. Thermal expansion increases significantly above 200°C, so it is not suitable for continuous high-temperature service.
Q4: What melting grades can you supply?
A: VIM for regular precision parts. VIM+VAR for high-end optical and semiconductor components to reduce inclusions.
Q5: Can 4J36 be used for glass sealing?
A: Not recommended. Its expansion curve does not match borosilicate glass at sealing temperature. 4J29 (Kovar) is the proper choice for glass-metal hermetic sealing.