AVAILABLE IN MANY FORMS
Future Alloys can provide the Highest Quality Alloy 36 / Invar 36 materials in many forms including:
Alloy 36 / Invar 36 Block, Rod, Bar, Strip, Sheet, Plate, Wire, Cube, Crucibles and Ingots.
We can supply be-spoke sizes and our sales team have many years of experience and can offer you technical information and advice for all the materials we deal with.
CUSTOM MACHINING
Do you have a special application for Alloy 36 / Invar 36 that needs custom machining?
Special cutters, feeds and cutting fluids are essential to complete Invar 36 machining without a detrimental effect to the material.
Future alloys have all the experience and equipment necessary to precision machine Invar 36 alloys to the highest specifications.
Please be as specific as possible, for example:
“Please quote for 8 off, 30mm diameter pure Invar 36 rods, in 1m lengths”
Classified as a controlled low expansion alloy Invar 36 has one of the lowest thermal expansion of all alloys and metals, a near zero coefficient of linear thermal expansion between the standard room temperature, 20 °C and 230 °C. It is a very workable material and easy to machine.
COEFFICIENT OF THERMAL EXPANSION:
With its 36 % nickel content Invar 36 has one of the lowest thermal expansion of all alloys and metals, a near zero coefficient of linear thermal expansion between the standard room temperature, 20 °C and 230 °C (less than 1.3 x 10-6°C-1).
WELDABILITY AND DUCTILITY:
Invar is weldable, ductile and doesn’t show signs of stress corrosion cracking.
MACHINABILITY:
Alloy 36 / Invar 36 ‘free-cut’ is specially formulated to be easier to machine than standard invar and can be processed using conventional tooling and techniques. It has similar machining attributes to stainless steel.
STRENGTH AND TOUGHNESS:
High strength and toughness at low cryogenic temperatures
STANDARDS AND SPECIFICATIONS
The superalloy complies with the following specifications:
ASTM B388
DIN 1.3912
UNS K93600
MIL I-16598
MIL I-23011 Class 7
WS 1.3912
TRADE NAMES:
The superalloy is also available under the following trademarks:
Ametek 936(tm)
Nilo 36(tm)
Pernifer 36
Name: Alloy 36 / Invar 36
Trade names: Ametek 936™, Nilo 36™ and Pernifer 36™
Type: Controlled Expansion Alloy
Chemical sign: FeNi36, 64FeNi in the United States
Thermal expansion: 4.9 ppm/°F (75°F to 842°F), 8.9 ppm/°C (25°C to 450°F)
Thermal conductivity: 72.6 Btu-in/ ft² / hr/ °F, 10.5 W /m þ K
Typical linear coefficient of thermal expansion (cm per cm): 1.72 X 10(-6)/ºC ( 30ºC to 200ºC )
Temperature coefficient of electrical resistivity: 0.0011 per °C, 0.0006 per °F
Curie temperature: 535°F, 279 °C
Hardness on Rockwell scale: 70 (annealed), 88 (half hard)
Yield Strength: 40 ksi
Tensile strength: from 85,000 psi (annealed) to 120,000 psi (hard)
Specific gravity: 8.05 g / cm3
Density: 8055 kg/cu m, 0.291 lb/cu in
Inflection point: 375°F, 191°C
Melting point: 2600°F , 1427 °C
Electrical resistivity: 495 ohm-cir mil /ft, 820 microhm-mm
Elongation: 30 %
Proof stress: 310 N / mm2
Alloy 36 / Invar 36 is a controlled expansion metal formed by nickel-iron alloys. It is also available under, Ametek 936™, Nilo 36™, and Pernifer 36™ trade names, and sometimes called ‘invar steel’ and ‘free cut’ invar. Classified as a single phase alloy it is composed of the main elements nickel (36%) and iron (63%) and other constituents cobalt, sulfur, phosphorus, carbon, silicon, manganese and chromium.
There are three types of the alloy available on the market today; standard invar, super invar (invar 32-5) and free machining invar (invar 36), the name invar originating from “invariable”. All are characterised by having a very low thermal expansion created by its 36% nickel content, but have marginally different properties according to the composition mix.
Alloy 36 / Invar 36 is the ‘free-machining’ version which is formulated to be easier to machine and process, and better for mass producing components which have intricate shapes and / or require machining to close tolerances. It is a derivative of Invar™ or standard invar which has similar properties but is not as machining friendly as Invar 36.
Together with a near zero thermal expansion Alloy 36 provides a high retention of strength and toughness at cryogenic temperatures, making it ideal for a range of both low temperature and low expansion applications. The alloy is suited to applications where changes in temperature must not affect the materials dimensions, including tooling for aerospace composites, radio and electronic devices, and structural supports in precision equipment such as thermostats, measuring devices, lasers, and cryogenic instruments. As well as being extensively used in the opto-mechanical industry, it is also widely used in the most common household electric appliances such as toasters, irons, TV-s or cookers. Its importance is increasing and will likely be used in even more devices in future, particularly in the electrical, telecommunication and gas industries.
Exact composition for invar can vary slightly between manufacturers and suppliers, so caution should be applied to ensure the grade purchased meets your application. Future alloys can advise the suitability for your application.
Alloy 36 is commonly employed in electronic equipment such as radios, laser systems and thermostats.
As a part of the Ni-Fe alloys’ family, invar 36 is used for shadow masks, frames, cathode ray tube gun parts, filters cell phone networks and tank membranes for natural gas transport ships. It’s used in appliances where not only a minimum thermal expansion but also a high dimensional stability is needed, such as optical devices, motor valves, laser cutting or fine line etching.
Laboratory devices, precision and scientific instruments also contain it.
Low expansion alloys are used when very small dimensional tolerance, chemical etching performance and high cleanliness are required. This typically happens in the electrical industry where there’s the pressure to make gadgets smaller and smaller. New requirements keep showing up in the technology industry and in order to keep up with the pace technology demands, invar and its derivatives need to be continually developed.
Large commercial aircraft have been using increasing amounts of advanced composites (primarily carbon fibers in an epoxy resin matrix) for component parts such as aircraft control surfaces, body fairings and structural supports.
lnvar 36 has now become the material of choice for tooling moulds for many commercial airplane manufacturers.
Advanced composite components are manufactured by consolidating and curing multiple layers of resin impregnated carbon fibers against a solid mold surface. Processing them requires applying heat and pressure via the mould.
Aircraft surfaces must be precisely aerodynamic, and the components dimensionally accurate advanced composites. It is therefore essential that the thermal expansion mismatch between the composite material and the mold is minimised during the 177°C cure cycle. If there is a significant difference in coefficient of thermal expansion (CTE), inaccurate part dimensions and warpage of the composite components will occur.
Invar 36 tooling due to its low rate of expansion more successfully produces accurate parts over traditional tooling materials previously used. These traditional materials included soft tooling such as fiberglass, machinable epoxy boards, high density foam, clay or wood/plaster, and hard tooling such as aluminium or mild steel.
Invar 36 combines robustness, durability, accuracy and stable dimensions which make it ideal for mass production tooling moulds.
Aerospace applications impose many challenging conditions on the equipment such as acceleration during launch, effect of gravity as orbit is achieved, vibration, vacuum, and thermal variation. This causes continuous stress on the equipment.
The requirements of material for opto mechanical space applications are low thermal expansion, and to be dimensionally stable. Most solid materials expand when their temperature is increased however in space dimensional stability is essential, that is, how to control it and keep it within specific limits.
Aerospace Optical Mirror Mounts are used to mount optical mirrors in a stable stationary position in laser or optical systems.
To operate effectively the mount has to be ultra stable, exert low stress on the optics to minimize optical surface distortion, have high stiffness to maintain the optic alignment, maintain the specified tolerance in the operational temperature range, maintain the position of the optical element throughout its assigned life time, and have minimum mount size and weight.
Long term dimensional stability is required for support structures in many instruments having optical components like mirror mounts. For example, optical imaging systems on space flights such as the Saturn bound Cassini spacecraft impose very strict requirements on the optical mounts supporting the camera system. Not only must the material meet the dimensional stability requirements, it must also be machinable and have adequate mechanical strength.
Invar 36 is a suitable and widely used material for space applications due to its low coefficient of thermal expansion (CTE), and because its mechanical and dimensional stability properties can be controlled and modified using specific heat treatment and cold working processes.
Some typical applications include lens and mirrors cells, interfacing spacers between optics and other structures, optical measuring equipment, metering rods for telescopes and laser cavity structures.
Invar 36 has been discovered very significant for containers that are utilized to transport liquid natural gas (LNG) on tankers. It reduces the low temperature cryogenic contraction effect and virtually eliminates thermal induced stresses.
Ships and other vessels that carry liquid cargo such as Liquefied Natural Gas (LNG) have to withstand severe conditions externally and internally. During shipment LNG is supercooled to liquid form at -162 degrees C and pumped into container tanks. Traditional steels become brittle at such low temperatures so Invar 36 with its suitable properties and weldability is increasingly being used as a lining material for the containers.
Invar is used for bimetallic strips for controllers which capitalises on the effect of two different metals with different coefficients of linear expansion causing movement at set temperatures. A bimetallic strip metal is made by laminating two metals together which have different rates of expansion. Bimetallic strips are used in many applications including clocks, thermostats, thermometers, circuit breakers, temperature gauges, time delay relays, lamp flashers, fluorescent lamp starters, household devices such as irons, chip fryers, ovens, grills and many more.
For some applications the bimetallic strip is shaped into a coil and when heated or cooled, the metals making up the strip expand and contract at different rates. When this coiled strip is heated, the metal on the inside expands more and the strip unwinds, when cooled the strip re-coils. For a typical switch mechanism a temperature adjustment lever is connected to the center of the coil and a mercury switch is mounted at the end of the coil. When the coil winds or unwinds, it instructs or tips the mercury switch one way or the other, and triggers an electrical circuit.
Bimetallic thermometer gauges use quick reacting bimetal coils. They are manufactured from two cold-welded metal strips with different thermal expansion coefficients and rotate in proportion to temperature. The rotary movement is conveyed to the pointer with low friction. They can be used for numerous industrial applications including; the petroleum industry, heating and ventilation equipment, food processing, water treatment plants, chemical processing, air conditioning, the iron and steel industry.
Invar is also used for special joints, balance wheels, tooling, pendulums and other parts of watches, magnetic shielding, resonant cavities for radars, mold for boat and aircraft parts, precision measurement constructions and condenser plates, electric transformers, spacers, metrology devices, echo boxes in cell phones, high voltage transmission lines and specialised frames and numerous other applications.