ASTM F30 Iron-Nickel Sealing Alloy
UNS K94600 (Alloy 46) Forgings: Rings, Bars, Discs and Flanges
Technical data and forged product range for the 46 % nickel iron-nickel sealing alloy specified in ASTM F30.
What is UNS K94600?
UNS K94600 is an iron-nickel controlled-expansion alloy containing nominally 46 % nickel with the balance iron. It is specified in ASTM F30 and is also known as Alloy 46, 46 Alloy, NILO 46 and Pernifer 46. Its coefficient of thermal expansion corresponds to that of soft soda-lime and lead glasses, and the alloy is used for glass-to-metal seals, lamp and electron-tube components, hermetic packages and thermostat parts.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. The company supplies UNS K94600 as forged rings, seamless rolled rings, forged round bars, discs, flanges, sleeves, bushings, shafts and tube sheets. Material is ultrasonically tested to EN 10228-3 or ASTM A388 and certified to EN 10204 3.1 or 3.2. Enquiries: sales@steelforgepieces.com, +86 189 2135 9659.
- UNS number
- K94600
- Common name
- Alloy 46
- Specification
- ASTM F30
- Nickel, nominal
- 46 %
- Density
- 8.17 g/cm³
- Curie temperature
- 460 °C
- Melting point
- 1427 °C
- Forged size range
- Ø80 to 6000 mm
Material description
The thermal expansion of iron-nickel alloys varies with nickel content. At approximately 36 % nickel the expansion is close to zero at room temperature, and expansion increases as the nickel content rises. At 46 % nickel the expansion of the alloy corresponds to that of soft glass, which is the basis for its inclusion in ASTM F30 as 46 Alloy. In a glass-to-metal seal the metal and the glass then expand and contract at similar rates, and the seal remains hermetic through thermal cycling.
The Curie temperature of the alloy is approximately 460 °C. The alloy is ferromagnetic below this temperature, and its expansion curve shows an inflection in the same region. Sealing operations and service temperatures are normally kept below the Curie point.
Designations and cross references
| UNS | K94600 |
|---|---|
| ASTM | ASTM F30, 46 Alloy (Standard Specification for Iron-Nickel Sealing Alloys) |
| Military and aerospace | MIL-I-23011 Class 4, AMS-I-23011 Class 4 |
| China | 4J46 (GB/T 15009 precision expansion alloys), closest equivalent, verify limits before substitution |
| Trade names | NILO 46, Pernifer 46, Glass-Seal 46, CarTech Glass Sealing 46 Alloy |
| Also written as | Ni46, 46 Ni, Alloy 46, Nickel Alloy 46, Glass sealing alloy 46 |
Trade names are the property of their respective owners and are listed for identification only.
Chemical composition of UNS K94600
Composition limits are those given in ASTM F30 for 46 Alloy. Cobalt may be present as an incidental element. Each heat is analysed by optical emission spectrometry and the result is reported on the material certificate.
| Element | Ni | Cr | Mn | Si | C | Al | P | S | Fe |
|---|---|---|---|---|---|---|---|---|---|
| Alloy 46 | 46.0 nom. | 0.25 max | 0.80 max | 0.30 max | 0.05 max | 0.10 max | 0.025 max | 0.025 max | Bal. |
Source: ASTM F30-96 (2017), Table 1, 46 Alloy.
Thermal expansion
The table gives the mean coefficient of linear thermal expansion measured from 30 °C to each stated upper temperature. The two ranges marked with an asterisk are acceptance limits in ASTM F30 Table 2. The remaining values are typical values from Table X1.1 of the same standard.
| Temperature range | UNS K94600 | Temperature range | UNS K94600 |
|---|---|---|---|
| 30 to 300 °C | 7.5 | 30 to 700 °C | 10.7 |
| 30 to 350 °C | 7.1 to 7.8 * | 30 to 800 °C | 11.6 |
| 30 to 400 °C | 7.5 | 30 to 900 °C | 12.5 |
| 30 to 500 °C | 8.2 to 8.9 * | 30 to 1000 °C | 13.4 |
| 30 to 600 °C | 9.8 | ||
Source: ASTM F30-96 (2017), Table X1.1 (46 Alloy). * Values marked with an asterisk are the specification requirements of ASTM F30-96 (2017) Table 2.
Physical and mechanical properties
| Property | Metric | Imperial |
|---|---|---|
| Density, specific gravity | 8.17 g/cm³ | 0.295 lb/in³ |
| Curie temperature | 460 °C | 860 °F |
| Melting point | 1427 °C | 2600 °F |
| Electrical resistivity | 47 µΩ·cm | 277 Ω·cmil/ft |
| Thermal conductivity | 0.11 W/cm·°C (11 W/m·K) | 79.2 BTU·in/ft²·h·°F |
| Specific heat | 0.50 J/g·°C | 0.12 cal/g·°C |
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength | 552 MPa | 80 ksi |
| Yield strength (0.2 % offset) | 242 MPa | 35 ksi |
| Elongation | 30 % | 30 % in 2 in. |
| Hardness, annealed | 80 HRB | 80 HRB |
| Modulus of elasticity | 159 GPa | 23 × 10³ ksi |
Source: ASTM F30-96 (2017). Values are typical for the annealed condition and are given for design guidance. They are not a guarantee for any particular heat or section size.
Forged product forms and sizes
UNS K94600 is produced by open-die forging and seamless ring rolling, then rough machined or finish machined to the customer's drawing. The table gives typical order sizes for this grade.
| Product form | Typical size range | Notes |
|---|---|---|
| Forged rings, seamless rolled rings | OD 150 to 2000 mm, height up to 600 mm | Rectangular or contoured section |
| Forged round bars | Ø 60 to 600 mm, length up to 4000 mm | Square and flat bar also available |
| Forged discs and blanks | Ø 100 to 1500 mm, thickness 20 to 400 mm | Solid or centre-bored |
| Forged flanges | To drawing, up to 1500 mm | Weld neck, blind, slip-on, special |
| Forged sleeves, bushings, hollow bar | OD 100 to 1200 mm, ID from 50 mm | Trepanned or mandrel forged |
| Forged shafts and stepped shafts | Ø 60 to 500 mm, length up to 4000 mm | Straight, stepped or flanged |
| Forged tube sheets and blocks | To drawing | Rough or finish machined |
| Piece weight | 10 to 3000 kg | Single pieces and prototypes accepted |
Plant envelope across all grades: Ø100 to 6000 mm, 10 to 15,000 kg, length up to 12,000 mm, on 1 t, 3 t, 6 t and 9 t forging hammers, a 4500 t hydraulic press and 3 m and 6 m ring-rolling mills.
Production route
Gas porosity, non-metallic inclusions and coarse or mixed grain structure affect seal integrity. These are controlled at the melting, forging and heat treatment stages.
- Melting
EAF and VOD followed by electroslag remelting (ESR), or VIM with ESR or VAR where a cleaner structure is required. Remelting reduces sulphur, phosphorus and gas content and improves inclusion distribution.
- Open-die forging or ring rolling
Billets are heated to approximately 1120 to 1180 °C and finish forged above approximately 900 °C. A forging reduction of at least 4:1 is normally applied to break down the as-cast structure and obtain a uniform grain through the section.
- Heat treatment
Supplied in the annealed condition in accordance with ASTM F30. For parts that will be sealed to glass, the annealing atmosphere (vacuum, dry hydrogen or wet hydrogen) and the cycle are agreed before production, since they determine the surface oxide condition.
- Machining
Rough machined with an agreed allowance, or finish machined to drawing, including bores, grooves, flange faces and sealing surfaces.
- Testing and inspection
Chemical analysis by optical emission spectrometry, tensile testing to ASTM E8/E8M, hardness testing, grain size to ASTM E112, and ultrasonic testing to EN 10228-3, ASTM A388 or SEP 1921. Thermal expansion can be verified by push-rod dilatometry to ASTM E228 on request.
- Certification and dispatch
EN 10204 3.1 certificate as standard, or EN 10204 3.2 witnessed by TÜV, SGS, BV or Lloyd's. Heat number marking, export packing and full shipping documents.
Applications
- Glass-to-metal seals with soft soda-lime and lead glasses
- Hermetic feedthroughs, headers and packages for sensors and semiconductors
- Electron tubes, vacuum devices and lamp components
- Reed switches, relays and contact assemblies
- Telecommunications hardware and microwave components
- Thermostat, temperature regulator and bimetal parts
- Ceramic-to-metal sealing where a matched moderate expansion is required
- Instrument and fixture parts requiring predictable dimensional change
Alloy 46 is most commonly stocked as strip and wire. Forged material is used where the section is too large or too thick to be produced from those forms, for example ring blanks for sealing fixtures, bar for machined feedthrough bodies and headers, discs for covers and flanges, and sleeves for housings.
Information required for a quotation
A dimensioned sketch is sufficient for an initial quotation. A full drawing is not required.
- Drawing or finished dimensions, and whether the part is required as forged or machined
- Quantity, and whether the order is a one-off, a prototype or a repeat order
- Governing specification and edition, for example ASTM F30 46 Alloy
- Delivery condition and any required annealing atmosphere
- Testing scope: ultrasonic class, tensile, grain size, dilatometry
- Certificate type (EN 10204 3.1 or 3.2) and destination port
Request a quotation
Send a drawing or the required dimensions. Single pieces, prototype quantities and series orders are all quoted.
Frequently asked questions
What is UNS K94600?
UNS K94600 is the Unified Numbering System designation for Alloy 46, an iron-nickel controlled-expansion alloy containing nominally 46 % nickel with the balance iron. It is specified in ASTM F30 and is used mainly for glass-to-metal seals with soft soda-lime and lead glasses, for lamp and electron-tube components, and for hermetic electronic packages.
Which standards cover UNS K94600?
The governing specification is ASTM F30, Standard Specification for Iron-Nickel Sealing Alloys, where the grade appears as 46 Alloy. It is also covered by MIL-I-23011 Class 4 and AMS-I-23011 Class 4. The closest Chinese designation is 4J46 under GB/T 15009.
What is the thermal expansion coefficient of Alloy 46?
Typical mean coefficients are approximately 7.5 µm/m·°C over 30 to 300 °C and 30 to 400 °C, rising to 9.8 over 30 to 600 °C and 13.4 over 30 to 1000 °C. ASTM F30 Table 2 requires 7.1 to 7.8 over 30 to 350 °C and 8.2 to 8.9 over 30 to 500 °C.
What is the difference between Alloy 46, Alloy 42 and Invar 36?
All three are iron-nickel controlled-expansion alloys that differ mainly in nickel content, which determines their expansion. Invar 36 contains approximately 36 % nickel and has near-zero expansion near room temperature. Alloy 42 contains approximately 42 % nickel and matches harder glasses and ceramics. Alloy 46 (UNS K94600) contains approximately 46 % nickel and has a higher expansion that matches soft soda-lime and lead glasses.
Is UNS K94600 magnetic?
Yes. Alloy 46 is ferromagnetic at room temperature and loses its ferromagnetism above its Curie temperature of approximately 460 °C (860 °F). The inflection in its expansion curve occurs in the same temperature region, and sealing designs are normally kept below it.
Can UNS K94600 be open-die forged into rings and bars?
Yes. Jiangyin Jiangnan Metal Co., Ltd. open-die forges and ring-rolls UNS K94600 into forged rings, seamless rolled rings, round bars, discs, flanges, sleeves, bushings, shafts and tube sheets. Billets are normally heated to approximately 1120 to 1180 °C and finish forged above approximately 900 °C, then annealed to obtain a uniform grain structure before machining.
What tests and certificates are supplied?
Chemical analysis, room temperature tensile testing, hardness and grain size as standard. Ultrasonic testing to EN 10228-3, ASTM A388 or SEP 1921. Thermal expansion by dilatometry to ASTM E228 on request. Material is certified to EN 10204 3.1, or EN 10204 3.2 with third party witness such as TÜV, SGS, BV or Lloyd's.
What is the Chinese equivalent of UNS K94600?
The closest Chinese grade is 4J46 in the GB/T 15009 series of iron-nickel precision expansion alloys. It is a close but not always identical match to ASTM F30 46 Alloy, and the chemistry and expansion limits of both specifications should be compared before a substitution is approved.
What is the minimum order quantity and lead time?
Single pieces and prototype quantities are accepted. Lead time depends mainly on whether suitable material is already available as ingot or billet. A confirmed delivery date is given with each quotation.
How do I request a quotation?
Send the drawing or finished dimensions, quantity, specification, delivery condition and any testing or certification requirements to sales@steelforgepieces.com, or call +86 189 2135 9659.
Related grades
Forged forms across all grades: forged rings, seamless rolled rings, forged bars, forged flanges, forged discs, forged shafts, forged sleeves, forged tube sheets and open-die forging parts.
Manufacturer
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China. The company produces forged rings, seamless rolled rings, forged bars, discs, flanges, shafts, sleeves and tube sheets in carbon steel, alloy steel, tool steel, stainless steel, nickel alloys and controlled-expansion alloys including UNS K94600 (Alloy 46). The plant operates 1 t, 3 t, 6 t and 9 t forging hammers, a 4500 t hydraulic press and 3 m and 6 m ring-rolling mills, covering forgings from Ø100 mm to Ø6000 mm and 10 kg to 15,000 kg. The company employs approximately 460 people, including 9 senior engineers and 32 intermediate engineers, and supplies material certified to EN 10204 3.1 and 3.2.
Jiangyin Jiangnan Metal Co., Ltd., Open-Die Forging FactoryNo.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Phone, WhatsApp and WeChat: +86 189 2135 9659
Email: sales@steelforgepieces.com
Web: www.steelforgepieces.com
Data sources and disclaimer
Property data on this page is taken from ASTM F30-96 (2017), Standard Specification for Iron-Nickel Sealing Alloys, and is reproduced for engineering guidance only. Values are typical for the annealed condition and vary with heat, section size and processing route. Material should always be ordered to the current edition of the applicable specification. No warranty for any particular heat is given or implied.
Page reviewed by the engineering department of Jiangyin Jiangnan Metal Co., Ltd. Last updated .