Nickel-iron controlled-expansion alloy, ASTM F30
UNS K94800 (Alloy 48) forgings Open-die forged rings, seamless rolled rings, flanges, bars, discs, shafts, sleeves and tube sheets in 48% nickel-iron controlled-expansion alloy
- Nickel
- 48 %nominal, Fe balance
- Expansion 20–100 °C
- 8.5µm/m·°C
- Inflection point
- 460 °C860 °F
- Melting point
- 1450 °C2640 °F
- Standard
- ASTM F30W.Nr. 1.3922 / 1.3926 / 1.3927
UNS K94800 is a binary nickel-iron controlled-expansion alloy containing a nominal 48% nickel, with iron as the balance. It is also sold as Alloy 48, Nilo 48, Pernifer 48, Glass Seal 48 and Invar 48. Its coefficient of thermal expansion matches soft lead and soda-lime glasses, which makes it a standard material for glass-to-metal seals. It is also used for industrial thermostats operating up to 450 °C (840 °F). The governing specification is ASTM F30.
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, manufactures UNS K94800 forgings to ASTM F30 and ships worldwide. Material is melted by EAF + VOD + ESR, ultrasonically tested to EN 10228-3, SEP 1921 or ASTM A388, and certified to EN 10204 3.1 or 3.2. For a quotation against drawings, contact sales@steelforgepieces.com or +86-189-2135-9659.
What UNS K94800 is used for
The thermal expansion of UNS K94800 is matched to soft lead and soda-lime glass. A component made from the alloy can be fused directly into glass and will hold the seal through repeated heating and cooling.
The alloy has an inflection point of 460 °C and predictable expansion below that temperature, so it is also used for thermostat rods, bimetal thermostat elements and temperature regulators in industrial equipment operating up to 450 °C (840 °F).
Nickel-iron controlled-expansion alloys are supplied and used in the annealed condition. Cold work remaining in the material alters the coefficient of thermal expansion, so forgings intended for glass sealing are annealed after forming. Heat treatment records should be supplied with the material certificate.
Equivalent designations and standards
UNS K94800 is listed under several trade and national designations. The following all describe the same 48% nickel-iron controlled-expansion alloy.
| System | Designation |
|---|---|
| UNS (USA) | K94800 |
| ASTM | ASTM F30, iron-nickel sealing alloys, Alloy 48 |
| Werkstoff / DIN | 1.3922, 1.3926, 1.3927 (DIN 17745) |
| AFNOR (France) | NF A54-301 |
| AWS | AWS 092 |
| Trade names | Alloy 48, Nilo 48, Pernifer 48, Glass Seal 48, Invar 48, Magnifer 50, SUPRA 50 |
Chemical composition of UNS K94800
Chemical composition limits for UNS K94800 in weight percent. Cobalt may be present as an incidental element and is reported separately.
| Element | Ni | Cr | Mn | Si | C | Al | P | S | Fe |
|---|---|---|---|---|---|---|---|---|---|
| Alloy 48 | 48 | 0.25 max | 0.80 max | 0.30 max | 0.05 max | 0.10 max | 0.025 max | 0.025 max | Bal. |
Mechanical properties
Typical room temperature mechanical properties of UNS K94800 in the annealed condition.
| Material | Ultimate tensile strength | Yield strength 0.2 % | Elongation | ||
|---|---|---|---|---|---|
| psi | MPa | psi | MPa | ||
| Alloy 48 | 75,000 | 520 | 38,000 | 260 | 43 % |
Physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 8.2 g/cm³ | 0.296 lb/in³ |
| Melting point | 1450 °C | 2640 °F |
| Inflection (Curie) point | 460 °C | 860 °F |
| Thermal conductivity | 16.7 W/m·°C | 116 Btu·in/ft²·h·°F |
| Mean expansion coefficient, 20–100 °C | 8.5 µm/m·°C | 4.7 × 10⁻⁶ in/in·°F (70–212 °F) |
| Mean expansion coefficient, 20–300 °C | 8.3–9.3 µm/m·°C | 4.6–5.2 × 10⁻⁶ in/in·°F (70–572 °F) |
| Maximum service temperature, thermostats | 450 °C | 840 °F |
Heat treatment and annealing
UNS K94800 is not precipitation hardenable. Annealing produces a uniform structure and removes cold work that would otherwise alter the expansion coefficient.
| Treatment | Temperature | Atmosphere | Cooling |
|---|---|---|---|
| Anneal | 850–1000 °C (1560–1830 °F) | Protective atmosphere | Air or water |
Holding time depends on section thickness. Nickel-iron alloys oxidise readily at annealing temperature. Where a non-oxidising atmosphere is not available, leave sufficient machining stock on the part for clean-up after heat treatment.
UNS K94800 forged products we manufacture
Jiangyin Jiangnan Metal Co., Ltd. forges UNS K94800 to customer drawings or dimensional requirements in the following forms.
Rings
- Forged rings
- Seamless rolled rings
- Valve seat rings
- Retaining rings
Bars and shafts
- Forged round bars
- Forged shafts
- Eccentric shafts
- Crankshafts
- Spindles
Flat and hollow
- Forged discs and disks
- Forged flanges
- Forged tube sheets
- Forged tubes and pipes
- Sleeves and bushings
Components
- Valve stems and bodies
- Valve blocks
- Forged nozzles
- Manifolds and wheels
- Gears
Related product pages: forged rolls, forged tube sheets, forged valve seat rings.
Typical applications
- Glass-to-metal sealsForged shafts, pipes, tubes, tube sheets and flanges for seals in soft lead and soda-lime glasses, microelectronic components, vacuum devices, radio valves and electric lamp bulbs.
- Thermostats and temperature controlThermostat rods, bimetal thermostat elements and temperature regulators for industrial service up to 450 °C.
- Semiconductor and electronicsRolled rings and shafts for semiconductor lead frames, precision condenser blades, radar and microwave cavity resonators, echo boxes and filters for mobile telephones, magnetic shielding and small transformers.
- Aerospace composite toolingRolled rings and forged shafts for composite layup tooling and advanced composite moulds that must hold dimension through the cure cycle.
- Instruments and metrologyOpen-die forgings for dimensionally stable instruments, optical devices, positioning devices, scientific instruments, electrical circuit breakers, clock balance wheels and pendulum clocks.
- Cryogenic and LNGForged pieces and nozzles for LNG tanker containment and transfer lines.
- ValvesForged valve stems, valve bodies, valve blocks and valve seat rings for ball, check, globe, gate and plug valves and for strainers.
Melting, forging, testing and certification
Melting route
UNS K94800 for forging is melted by EAF + VOD + ESR: electric arc furnace melting, vacuum oxygen decarburisation refining and electroslag remelting. Electroslag remelting lowers sulphur and non-metallic inclusion content, which is required for consistent glass sealing performance.
Non-destructive testing
Finished UNS K94800 forgings are ultrasonically tested to EN 10228-3, SEP 1921 or ASTM A388, to the quality class stated on the order. Dye penetrant and magnetic particle inspection are available where the geometry requires it.
Certification
Orders are supplied with a material certificate to EN 10204 3.1 covering chemical analysis, mechanical test results, heat treatment records and non-destructive test reports. EN 10204 3.2 certification with third party inspection is available on request.
Frequently asked questions about UNS K94800
What is UNS K94800?
UNS K94800 is a binary nickel-iron controlled-expansion alloy containing a nominal 48% nickel, with iron as the balance. It is commonly called Alloy 48, Nilo 48, Pernifer 48 or Glass Seal 48. Its coefficient of thermal expansion matches soft lead and soda-lime glasses, which makes it a standard choice for glass-to-metal seals. It is also used for industrial thermostats operating up to 450 °C (840 °F). The governing specification is ASTM F30.
What is UNS K94800 equivalent to?
UNS K94800 is equivalent to Alloy 48, Nilo 48, Pernifer 48, Glass Seal 48, Invar 48, Magnifer 50 and SUPRA 50. In German designations it corresponds to Werkstoff numbers 1.3922, 1.3926 and 1.3927 under DIN 17745. It is covered by ASTM F30 in the United States, AFNOR NF A54-301 in France, and AWS 092 for welding products.
What is the chemical composition of UNS K94800?
UNS K94800 contains 48% nickel nominal, with maximum limits of 0.25% chromium, 0.80% manganese, 0.30% silicon, 0.05% carbon, 0.10% aluminium, 0.025% phosphorus and 0.025% sulphur. Iron makes up the balance. Cobalt may be present as an incidental element and is reported separately.
What is the thermal expansion coefficient of UNS K94800?
The mean coefficient of thermal expansion of UNS K94800 is approximately 8.5 µm/m·°C between 20 and 100 °C, and 8.3 to 9.3 µm/m·°C between 20 and 300 °C. In imperial units that is about 4.7 x 10-6 in/in·°F from 70 to 212 °F. The inflection (Curie) point is 460 °C (860 °F).
What are the mechanical properties of UNS K94800 in the annealed condition?
In the annealed condition UNS K94800 has an ultimate tensile strength of 520 MPa (75,000 psi), a 0.2% yield strength of 260 MPa (38,000 psi) and an elongation of 43%. Density is 8.2 g/cm3 and the melting point is 1450 °C (2640 °F).
How is UNS K94800 annealed?
UNS K94800 is annealed between 850 and 1000 °C (1560 to 1830 °F) in a protective atmosphere, held for a time appropriate to the section thickness, then air or water cooled. Nickel-iron controlled-expansion alloys are supplied and used in the annealed condition, because cold work remaining in the material alters the coefficient of thermal expansion.
What forged shapes are available in UNS K94800?
Jiangyin Jiangnan Metal Co., Ltd. produces UNS K94800 as open-die forged rings, seamless rolled rings, flanges, round bars, shafts, discs and disks, sleeves, bushings, tubes, tube sheets, spindles, gears, valve stems, valve seat rings, valve blocks, nozzles, manifolds, forged rolls, crankshafts and eccentric shafts. Parts are forged to customer drawings or dimensional requirements.
How is UNS K94800 melted and tested?
Jiangyin Jiangnan Metal Co., Ltd. melts UNS K94800 by an EAF + VOD + ESR route: electric arc furnace melting, vacuum oxygen decarburisation refining and electroslag remelting. Finished forgings are ultrasonically tested to EN 10228-3, SEP 1921 or ASTM A388 as specified by the customer.
What certification is supplied with UNS K94800 forgings?
UNS K94800 forgings are supplied with material certificates to EN 10204 3.1. Third-party inspection certificates to EN 10204 3.2 are available on request. Chemical analysis, mechanical test results, heat treatment records and non-destructive testing reports are included.
What is the difference between UNS K94800 (Alloy 48) and Invar 36?
Both are nickel-iron controlled-expansion alloys, but they are matched to different expansion rates. Invar 36 contains 36% nickel and has the lowest thermal expansion of the family, close to 1.5 µm/m·°C. UNS K94800 contains 48% nickel and expands at approximately 8.5 µm/m·°C, matched to soft lead and soda-lime glass. Invar 36 is specified where minimum dimensional movement is required. UNS K94800 is specified where the part must seal to soda-lime or soft lead glass.
Who supplies UNS K94800 open-die forgings?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China that manufactures UNS K94800 (Alloy 48) forgings to ASTM F30 and ships worldwide. The company is located at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Enquiries: telephone +86-189-2135-9659, email sales@steelforgepieces.com. Send a drawing or the required dimensions and the factory will quote.
How do I request a quotation for UNS K94800 forgings?
Send the drawing or the required dimensions of the UNS K94800 forged part to sales@steelforgepieces.com, or call +86-189-2135-9659. State the finished or rough dimensions, quantity, applicable standard, required heat treatment condition, ultrasonic testing class and certificate level. Jiangyin Jiangnan Metal Co., Ltd. will reply with a price and lead time.
Request a quotation for UNS K94800 forgings
Send the drawing or the dimensions required. State the quantity, the applicable standard, the heat treatment condition, the ultrasonic testing class and the certificate level. We will reply with a price and a lead time.
- Telephone / WhatsApp
- +86-189-2135-9659
- Factory
- No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Ships to
- Worldwide
About the manufacturer
Jiangyin Jiangnan Metal Co., Ltd.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China. We forge rings, seamless rolled rings, flanges, bars, discs, shafts, sleeves, bushings and tube sheets in carbon steel, alloy steel, tool steel, stainless steel and nickel-base alloys, including the controlled-expansion grades UNS K94800, Invar 36, Invar 42 and Ni-Span-C Alloy 902. Orders are supplied against drawings, with EN 10204 3.1 or 3.2 certification and ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388.
Jiangyin Jiangnan Metal Co., Ltd.No.1 Chengxiqiao Road, Zhouzhuang Town
Jiangyin City, Jiangsu Province, China
Telephone: +86-189-2135-9659
Email: sales@steelforgepieces.com
Web: www.steelforgepieces.com
Related controlled-expansion and nickel alloys
- Alloy 48: the same alloy under its common trade designation.
- Invar 36: 36% Ni, lowest expansion in the family, for dimensionally stable tooling.
- Invar 42: 42% Ni, matched to borosilicate glass and semiconductor lead frames.
- Ni-Span-C Alloy 902: constant-modulus alloy for precision springs and transducers.
- A286 and Incoloy A-286: precipitation-hardening iron-base superalloy.
- Incoloy DS, AISI 330 and Alloy 31: heat and corrosion resistant grades.
- All nickel alloy grades