Alloy 45 Forgings: Fe-45%Ni Controlled-Expansion Rings, Discs, Bars and Sleeves

Alloy 45 Fe-45Ni 45Ni-Fe Low Expansion Alloy 45 Nickel Alloy 45 ASTM F30 ASTM B753 ASTM E228 expansion test

Published: 12 May 2022 | Last updated: 12 August 2026 | Written and technically reviewed by the Jiangyin Jiangnan Metal Co., Ltd. Metallurgical Engineering Team

Quick answer

Alloy 45 is a controlled-expansion alloy of nominally 45% nickel and balance iron, whose thermal expansion sits between Alloy 42 and Alloy 48 and stays approximately linear up to about 440 °C. Above that temperature, which is its Curie point, the alloy loses ferromagnetic ordering and the expansion coefficient rises sharply. That sets the practical ceiling for any matched-expansion application.

Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, manufactures Alloy 45 as seamless rolled rings, forged discs, shafts, sleeves, flanges, tube sheets, blocks and round bars, supplied to ASTM F30, ASTM B753 or customer chemistry with EN 10204 3.1 certification (3.2 third-party witnessed on request). Contact: 0086-189-2135-9659 · sales@steelforgepieces.com.

Nominal chemistry: 45% Ni, balance Fe
Mean CTE 30-300 °C: ≈7.0-8.0 ×10⁻⁶/°C (typical)
Curie / linearity limit: ≈440 °C
Density: ≈8.17 g/cm³ (0.295 lb/in³)
Seals to: soft lead and soda-lime type glasses
Magnetic: yes, below the Curie point
Max ring OD forged here: 2,500 mm
Max single-piece weight: 8,000 kg

Nickel: 45%balance iron
CTE 30-300 °C: ≈7.5×10⁻⁶ /°C typical
Curie point: ≈440°C
Density: 8.17g/cm³
Max ring OD: 2,500mm
Max disc Ø: 1,800mm
Max shaft L: 8metres
Max piece: 8,000kg

What is Alloy 45?

Alloy 45 is a binary iron-nickel controlled-expansion alloy containing nominally 45% nickel with the balance iron. It belongs to the same family as Invar 36, Alloy 42, Alloy 46, Alloy 48 and Alloy 52. In all of these alloys the thermal expansion is tuned to a target value rather than merely being low, and nickel content is what tunes it. Raise or lower the nickel level and both the expansion coefficient and the temperature at which that expansion stays linear move together.

The mechanism is magnetic. Below the Curie temperature these alloys are ferromagnetic, and the magnetic ordering produces a volume effect that partially cancels ordinary thermal expansion, giving an unusually flat and predictable expansion curve. At the Curie point the magnetic ordering disappears, the cancellation stops, and the expansion coefficient jumps to a normal metallic value. Every controlled-expansion grade therefore has a hard functional ceiling rather than a gradual softening limit.

Alloy 45 sits between Alloy 42 and Alloy 48 on that curve: expansion high enough to work with soft lead and soda-lime type glasses, the ordinary glasses used in lamp envelopes, vacuum devices and many electronic packages, while still holding linearity to about 440 °C. That is roughly 60 °C higher than Alloy 42. In practice engineers choose Alloy 45 for one of three reasons.

To seal to soft glass. A glass-to-metal seal only stays hermetic if metal and glass shrink together as they cool from the sealing temperature. The nickel level of Alloy 45 is trimmed within its band to bring the metal onto the glass, so the cooled seal carries low residual stress or a controlled compressive stress.
To hold a dimension across a temperature swing. Composite-curing moulds, optical benches, laser and telescope structures, metrology fixtures and precision spacers all need a part that does not move as the shop or the autoclave heats up.
To act as the low-expansion leg of a bimetal. In thermostatic bimetal strip, one layer must expand far less than the other. Alloy 45 is one of the standard low-expansion components, and it appears under ASTM B753 for thermostat component alloys for that reason.

Naming caution. "Alloy 45" is a nickel-content nickname, not a protected designation. Different mills, distributors and drawings use it for chemistries that are close but not identical, and it is routinely confused with 45 Permalloy, a soft-magnetic alloy with a similar nickel level but a completely different purpose. Always state the chemistry band and the required expansion coefficient on the purchase order rather than relying on the trade name. The how-to-specify section below gives the wording.

Alloy 45 designations, equivalents and near neighbours

Unlike stainless grades, Fe-Ni controlled-expansion alloys are usually ordered by nominal nickel content plus the governing standard rather than by a single universal number. There is no single worldwide designation that every mill recognises for the 45% nickel grade, so the names below all point at the same chemistry region and should be treated as search terms, not as guarantees.

Table 1. Names and standards used for the 45% nickel controlled-expansion alloy
Designation / name	Where it comes from	Notes for procurement
Alloy 45	Industry shorthand	The common commercial name. Means "nominally 45% Ni, balance Fe". Not a protected or registered designation.
Fe-Ni 45 / 45Ni / Ni45	Chemistry shorthand	Used on European and Asian drawings. Unambiguous about intent; still needs a chemistry band attached.
Low Expansion Alloy 45	Distributor catalogues	Emphasises the controlled-expansion function rather than the sealing function.
ASTM F30	ASTM International	Specification for iron-nickel sealing alloys intended for glass sealing in electronic applications. Withdrawn by ASTM in 2024. Cite a specific revision, e.g. ASTM F30-96(2017), if you use it.
ASTM B753	ASTM International	Specification for thermostat component alloys. Covers the low-expansion components of bimetal strip, including the 45% nickel grade.
ASTM E228	ASTM International	Not a material specification. It is the push-rod dilatometer test method used to verify the expansion coefficient. Reference it whenever expansion is a contract property.
45 Permalloy	Soft-magnetic alloy family	Not the same thing. Similar nickel level, but specified for magnetic permeability, not expansion. Do not accept a substitution without checking which property is controlled.

Where a project needs a formally numbered material, most buyers either (a) name a neighbouring standardised grade whose expansion is close enough (see the comparison table), or (b) attach a chemistry and expansion sheet as an annex to the purchase order. Jiangyin Jiangnan Metal Co., Ltd. accepts orders either way and states all applicable designations on the material test certificate.

What is the chemical composition of Alloy 45?

Alloy 45 is nominally 45% nickel with the balance iron, and everything else in the analysis is there to be controlled rather than to contribute. Carbon, silicon, manganese and aluminium act as deoxidisers and residuals; chromium, titanium and zirconium are held down because they shift the expansion curve and interfere with the oxide layer that a glass seal has to bond to. The nickel band is the number that matters: a few tenths of a percent measurably moves both the expansion coefficient and the Curie point.

Table 2. Alloy 45 typical works chemistry band (wt %) as produced by Jiangyin Jiangnan Metal Co., Ltd.
Element	Typical limit (wt %)	Why it is controlled
Nickel (Ni)	45.0 nominal	Sets the expansion coefficient and the Curie temperature together. This is the controlling element.
Carbon (C)	0.05 max	Carbides disturb dimensional stability and can outgas at a glass seal. Kept low; decarburising anneals go lower still.
Manganese (Mn)	0.80 max	Deoxidiser and sulfur control. Excess raises expansion slightly.
Silicon (Si)	0.30 max	Deoxidiser. High silicon degrades the adherent oxide needed for glass wetting.
Chromium (Cr)	0.10 max	Residual only. Chromium forms a tenacious oxide that glass does not wet in the same way.
Aluminium (Al)	0.10 max	Deoxidiser residual; also densifies the oxide layer in small amounts.
Magnesium (Mg)	0.05 max	Deoxidiser / desulfuriser residual from ladle treatment.
Titanium (Ti)	0.00 / not added	Deliberately absent. Titanium getters oxygen and changes seal oxide behaviour.
Zirconium (Zr)	0.00 / not added	Deliberately absent for the same reason as titanium.
Phosphorus (P)	0.025 max	Impurity; hot-shortness and grain-boundary embrittlement.
Sulfur (S)	0.025 max	Impurity; sulfide inclusions are seal-leak and fatigue initiation sites.
Iron (Fe)	Balance	Matrix.

Values are the standard works band. Where a purchase order cites ASTM F30 (a named revision), ASTM B753, or a customer chemistry sheet, we melt to the band on the order and report the actual heat analysis on the EN 10204 certificate. For vacuum-device and hermetic-seal work we also report hydrogen, oxygen and nitrogen on request. Gas content, rather than chemistry, is the usual cause of seal failure.

The one thing to get right. Chemistry conformance does not guarantee expansion conformance. Two heats can both sit inside the nickel band and still differ measurably in coefficient of thermal expansion because of prior thermal history and residual stress. If matched expansion is functional for your part, make the expansion coefficient itself a contract property, with a value, a temperature band and the ASTM E228 test method stated, rather than the chemistry alone.

Physical and thermal properties of Alloy 45

The thermal numbers below are the ones that decide whether an Alloy 45 part works. The mechanical numbers matter mainly for handling, machining and structural sizing, since this is not a grade selected for strength.

Table 3. Alloy 45 typical physical properties, annealed condition, room temperature unless stated
Property	Typical value	Unit	Comment
Density	8.17	g/cm³ (0.295 lb/in³)	Use for forging-weight and RFQ calculations.
Mean coefficient of thermal expansion, 30-300 °C	≈7.0-8.0	×10⁻⁶ /°C	Verify per ASTM E228. Sits between Alloy 42 (≈5.3) and Alloy 48 (≈8.7). Trimmed within the nickel band to suit the mating glass.
Curie temperature / linearity limit	≈440	°C	The functional ceiling. Above it the expansion coefficient rises abruptly toward normal austenitic values.
Expansion above the Curie point	≈14-16	×10⁻⁶ /°C	Roughly double the controlled value. Any matched-expansion function is lost.
Modulus of elasticity (E)	≈145-150	GPa	Noticeably lower than steel (≈205 GPa). Allow for deflection in fixtures and moulds.
Thermal conductivity	≈13-15	W/m·K	Low. Large moulds and tools heat and cool slowly, so allow soak time.
Specific heat	≈500	J/kg·K	n/a
Electrical resistivity	≈0.45-0.50	µΩ·m	n/a
Magnetic behaviour	Ferromagnetic	n/a	Magnetic below ≈440 °C, paramagnetic above. The magnetic transition and the expansion transition occur together.
Melting range	≈1425-1450	°C	n/a

Typical values for the annealed condition, published for guidance. Actual certified values for your heat are reported on the EN 10204 certificate. Where expansion is functional, we supply dilatometer results to ASTM E228 over the temperature band you specify.

Mechanical properties of Alloy 45 forgings

Alloy 45 is a soft, ductile, austenitic-behaving alloy, chosen for dimensional behaviour rather than for strength. Annealed properties are close to a soft austenitic stainless steel; cold work raises strength substantially but also disturbs dimensional stability, so structural parts that must hold a dimension are normally supplied annealed and then stabilised.

Table 4. Alloy 45 typical mechanical properties by condition (room temperature, longitudinal)
Condition	Tensile strength	Yield (0.2%)	Elongation	Hardness
Annealed (typical forging delivery condition)	480-560 MPa	240-310 MPa	35-45%	130-160 HB
Stress-relieved after rough machining	490-570 MPa	260-330 MPa	32-42%	140-170 HB
Cold worked (bar / strip, not typical for forgings)	up to 800 MPa	up to 650 MPa	5-15%	up to 230 HB

Typical ranges for guidance. Alloy 45 is not a strength grade and is not heat-treatable by precipitation or martensitic transformation. Annealing and stress relief are the only useful thermal treatments. If your part needs both matched expansion and high strength, tell us at enquiry stage; the usual answer is a mechanical design change or a bimetallic construction rather than a different heat treatment.

Expansion & Curie-point explorer

Pick the grades you are considering, add your glass or ceramic, and see where each alloy stops behaving as a controlled-expansion alloy.

Overlay a mating material

Your maximum service temperature (°C)

Grades shown

Schematic curves built from typical published mean expansion coefficients and Curie temperatures for each grade; the transition is drawn as a smooth rise because real dilatometer traces bend over roughly a 40-60 °C window rather than stepping. Use this to understand grade behaviour and to shortlist, not as design data. For design, order a dilatometer trace to ASTM E228 on the actual heat.

Glass & ceramic seal matcher

Tell us what the metal has to seal or mate to and we will tell you which Fe-Ni grade matches it, including the cases where the answer is not Alloy 45.

Mating material

Highest temperature the joint sees (°C)

Glass expansion values are nominal figures for the named glass type over roughly 0-300 °C; individual glass formulations vary and the sealing designer must also consider the glass set point, the oxide layer, seal geometry and whether a matched or compression seal is intended. This tool shortlists a grade. It does not design a seal.

Service-temperature checker

Controlled-expansion alloys do not soften gradually. They stop working at the Curie point. Check your service temperature against it.

Grade

Maximum service temperature (°C)

What is the alloy doing?

Curie temperatures are typical published values and shift with the actual nickel level of the heat. Where the service temperature is within about 50 °C of the Curie point, treat the margin as insufficient and either move up a grade or have the transition measured on your heat.

Alloy 45 vs Invar 36, Alloy 42, Alloy 46, Alloy 48 and Alloy 52

These six grades are one alloy with six nickel levels, and nickel content moves expansion and Curie temperature in the same direction. Lower nickel gives you a lower expansion coefficient but a lower temperature ceiling; higher nickel raises the coefficient and buys you more temperature headroom. No single grade gives both, so the family runs to six members.

Table 5. Controlled-expansion Fe-Ni family: how the grades differ and when to pick each one
Grade	Nominal Ni	Mean CTE 30-300 °C	Approx. Curie / linearity limit	Typically matched to	Pick it when…
Invar 36	36%	≈1.5 (20-100 °C)	≈230 °C	Nothing. Used for near-zero movement	You want the least possible movement and the part never gets hot. Metrology, optical benches, LNG membranes, satellite structures.
Alloy 42	42%	≈5.3	≈380 °C	Hard sealing glass, alumina, silicon	Semiconductor lead frames, hard-glass seals, composite moulds where low expansion beats temperature range.
Alloy 45 this page	45%	≈7.0-8.0	≈440 °C	Soft lead and soda-lime type glasses	You need more temperature headroom than Alloy 42 gives, and an expansion in the 7-8 region. The middle of the family.
Alloy 46	46%	≈7.5-8.3	≈460 °C	Enamelling, resistor terminal bands, soft glass	Enamelled and vitreous-coated parts, where the alloy must survive the enamelling cycle without degassing.
Alloy 48	48%	≈8.5-9.0	≈500 °C	Soda-lime and soft lead glass	Soft-glass sealing with more temperature headroom than Alloy 45, or where the glass sits nearer 9.
Alloy 52	≈51%	≈9.5-10.2	≈510 °C	Soda-lime and potash-soda-lime soft glass	The classic soft-glass sealing grade. Semiconductor pin feed-throughs, reed switches, hermetic headers.

Typical published values for orientation. Individual mill bands and heat-to-heat variation shift these figures, and Alloy 45 in particular is reported differently by different sources. That is one more reason to make expansion a tested contract property. Jiangyin Jiangnan Metal Co., Ltd. forges every grade in this table, so our recommendation is not steered by what we happen to stock.

Honest answer to the most common question. If your only requirement is "seal to soda-lime glass", Alloy 52 or Alloy 48 is usually the better match than Alloy 45, because soda-lime sits near 9.2 ×10⁻⁶/°C. Alloy 45 earns its place when you need an expansion in the 7-8 region, when you are matching a specific soft lead glass, when the design is already qualified on Alloy 45, or when you want more temperature margin than Alloy 42 without going all the way up the nickel scale. Tell us the application and we will say if a different grade suits it better.

Controlled-expansion grade selector

Answer four questions to get a grade, the reasoning behind it, and the trade-off it carries.

1. What is the part for?

2. Highest temperature in service or process (°C)

3. Expansion you must match (×10⁻⁶/°C)

4. What form do you need?

A shortlisting aid based on the published typical values in Table 5. Final material selection remains the responsibility of your design authority and should account for seal geometry, glass set point, joining method, cyclic loading and qualification history.

What forged products are available in Alloy 45?

Jiangyin Jiangnan Metal Co., Ltd. manufactures Alloy 45 by four forging routes, selected by part geometry and order quantity. Alloy 45 is best known as a strip and wire alloy for electronics, but the same chemistry in forged section is what larger hardware needs: seal frames and housings, composite-mould structures, precision spacers, sight-glass and viewport rings, and instrument bodies.

Seamless rolled rings
Forged discs & hubs
Forged round bars
Forged shafts & spindles
Sleeves & bushings
Flanges
Tube-sheet blanks
Forged blocks
Seal frames & housings
Spacers & rings
Valve bodies & seat rings
Near-net-shape forgings to drawing

Route 1

Open-die forging

Long shafts, blocks, spindles and large discs. The default route for anything over about 500 mm in one dimension or outside the ring-mill envelope. Discs to Ø1,800 mm, shafts to 8 m, single pieces to 8,000 kg.

Route 2

Seamless ring rolling

Rings from 200 mm to 2,500 mm outside diameter, rectangular or contoured section. This is the most economical route for seal frames, viewport and sight-glass rings, mould rings and flange blanks, and it also gives the best circumferential grain flow.

Route 3

Upset forging

Short, large-cross-section discs and hubs where the input bar is upset rather than drawn. Efficient for thick spacers and flange blanks with a modest diameter-to-thickness ratio.

Route 4

Near-net-shape forging

Where the profile allows, forging closer to shape removes 30 to 50% of the rough machining. On a controlled-expansion alloy this matters twice over, because Alloy 45 is expensive per kilogram and slow to machine, so every kilogram of removed stock costs both material and shop hours.

How is Alloy 45 melted, forged and heat treated?

Melting route

Melting practice matters more for Alloy 45 than for a structural steel, because dissolved gas and inclusions decide whether a seal holds vacuum. Two routes are offered:

EAF + VOD + ESR. The standard route for structural, tooling and general controlled-expansion work. Electroslag remelting gives clean, sound, directionally solidified stock suitable for large rings and discs.
VIM + VAR. Vacuum induction melting followed by vacuum arc remelting, specified where the part forms a hermetic seal or operates in vacuum. This is the route to name when hydrogen, oxygen and nitrogen limits appear on your drawing.

Forging practice

Alloy 45 forges in a window of roughly 1,100-1,180 °C, with the finishing temperature kept above about 900 °C. The alloy is ductile and forgiving compared with a superalloy, but three points govern quality:

Reduction ratio ≥ 4:1 to break down the as-cast structure. Coarse residual cast grain is the usual cause of scattered expansion results and noisy ultrasonic traces.
Avoid sulfur pickup from the furnace atmosphere. Fe-Ni alloys are sensitive to hot-shortness from nickel sulfide at grain boundaries; reheating furnaces are run accordingly.
Uniform reduction. Uneven work leaves residual stress, and residual stress in a controlled-expansion part shows up later as dimensional drift after machining.

Heat treatment

Alloy 45 is not hardenable. There is no martensitic transformation and no precipitation cycle to exploit, so the useful treatments are these.

Table 6. Alloy 45 heat treatments and what each one is for
Treatment	Typical cycle	Purpose
Anneal	830-870 °C, hold, then controlled cool	Softening and grain refinement after forging. Standard delivery condition for forgings.
Stress relief	500-600 °C, hold, slow cool	Applied after rough machining to release machining stress before finish cuts. This is the step most often skipped and most often regretted.
Stabilising / dimensional-stability cycle	Thermal cycling through the intended service range	For moulds, fixtures and optics that must not drift. Cycles the part through service temperature several times so any residual movement happens before final machining, not in service.
Wet-hydrogen / decarburising anneal	Per seal specification	For glass-sealing surfaces: removes carbon and hydrogen so the seal does not gas or bubble at the interface.
Pre-oxidation before sealing	Per seal specification	Grows the controlled adherent oxide the glass wets and bonds to. Normally done by the sealing house rather than the forge, but it must be allowed for in the surface condition you order.

Cycles shown are typical works practice for forged sections and are adjusted for section thickness and the customer specification. Where a drawing names its own cycle, we run the drawing's cycle and record the furnace chart on the certificate.

The sequence that avoids dimensional complaints. Forge → anneal → rough machine leaving stock → stress relieve → (thermal cycle if the part must hold a dimension) → finish machine. Cutting straight from an as-forged bar to finished size on a controlled-expansion alloy is the most common cause of parts that measure correctly at the forge and wrong at the customer.

How do you machine and weld Alloy 45?

Machining

Alloy 45 machines like a soft austenitic stainless steel: gummy, work-hardening and hard on cutting edges. It is not difficult to machine, but habits carried over from carbon steel will cause trouble. Practical starting points are below.

Sharp, positive-rake coated carbide. Uncoated carbide dulls fast; ceramic is unsuitable at these speeds.
Turning around 40-70 m/min with a feed of 0.15-0.30 mm/rev. Keep the feed constant and never let the tool dwell, because the surface work-hardens under a rubbing edge and the next pass is worse.
Rigid setup, minimum overhang, generous flood coolant.
Take the machining stress out. Leave stock, stress relieve, then finish. On a part where dimension is the function, this is not optional.

Welding

Alloy 45 is readily welded by GTAW (TIG) and electron-beam welding, using a matched Fe-Ni filler. Two cautions specific to controlled-expansion alloys:

A weld is a local composition change, so it is also a local expansion change. Where matched expansion must hold across the joint, use matched filler and anneal after welding.
Keep sulfur and copper away from the joint. Fe-Ni alloys are sensitive to hot cracking from low-melting grain-boundary films. Clean the joint properly and keep sulfur-bearing marking and cutting fluids away from it.

Alloy 45 production capability at Jiangyin Jiangnan Metal

Jiangyin Jiangnan Metal Co., Ltd. has forged open-die parts and seamless rolled rings at Zhouzhuang Town, Jiangyin City since 2008 and exports to more than 40 countries. The envelopes below are the tested limits for Alloy 45 specifically; they differ from our carbon-steel limits because a controlled-expansion alloy needs more reduction, slower cooling and more thermal processing per kilogram.

Max ring OD: 2,500mm, seamless rolled
Min ring OD: 200mm
Max disc Ø: 1,800mm
Max shaft length: 8,000mm
Bar diameter: 25-500mm
Max single piece: 8,000kg
Typical lead time: 8-12weeks
Quotation: 24hours

Alloy 45 process flow, raw material to certificate

Raw materialEAF+VOD+ESR or VIM+VAR · heat traced · chemistry verified by OES
Forging1,100-1,180 °C · finish >900 °C · reduction ≥4:1
Controlled coolSlow cool · avoid uneven residual stress
Anneal830-870 °C · furnace chart recorded
Rough machineLeave stock · UT after rough turning
Stress relieve500-600 °C · slow cool · thermal cycling if specified
Test & NDEUT ASTM A388 / EN 10228-3 / SEP 1921 · dilatometry ASTM E228 on request
Certify & shipEN 10204 3.1 or 3.2 · marked · packed

Equipment used for Alloy 45 production

Table 7. Plant equipment qualified for Alloy 45 controlled-expansion forgings
Stage	Equipment	Capacity / capability
Forging, heavy	Free-die hydraulic press, 40 MN	Max ingot 12 t · max diameter 1,800 mm · max length 8,000 mm
Forging, medium	Free-die hydraulic press, 25 MN	Max ingot 6 t · faster cycle · preferred for shafts and bars
Forging, hammers	1 t, 3 t, 5 t and 9 t forging hammers	Smaller sections, upsetting and blocking operations
Ring rolling	Radial-axial ring mills, 3 m and 6 m	Max OD 2,500 mm · max height 600 mm · min wall 30 mm
Heat treatment	Bogie-hearth annealing furnace	8 × 4 × 2 m chamber · 1,100 °C max · ±5 °C uniformity
Heat treatment	Stress-relief / stabilising furnace	200-700 °C · ±3 °C uniformity · chart recorded per lot
NDT, ultrasonic	Phased-array ultrasonic system	ASTM A388 · EN 10228-3 · SEP 1921 · automated scan and report
NDT, surface	Penetrant and magnetic-particle lines	Surface indication detection on machined and as-forged surfaces
Lab, chemistry	Optical emission spectrometer	Full elemental analysis · calibrated daily against traceable standards
Lab, mechanical	Universal testing machine, impact and hardness testers	Tensile, Charpy V impact, HB / HRC / HV
Lab, metallography	Metallographic microscope	Grain size, inclusion rating, macroetch for grain flow
Lab, expansion	Push-rod dilatometry (partner laboratory)	Mean and instantaneous CTE per ASTM E228 over a specified band

Dilatometry to ASTM E228 is arranged through an accredited partner laboratory and reported as an annex to the EN 10204 certificate. Specify the temperature band you need measured, because a coefficient quoted without a band cannot be checked.

Alloy 45 forging weight calculator

Pick a shape, enter dimensions, get finished weight at 8.17 g/cm³ plus an estimated rough forging weight for your enquiry.

Shape

Outside diameter (mm)

Length (mm)

Machining allowance

Volume: 0
Finished weight: 0
Finished weight: 0
Rough forging: 0

Calculated at the Alloy 45 nominal density of 8.17 g/cm³ (0.295 lb/in³). The rough forging figure applies the allowance you selected and is an estimate for quotation only; the actual billet is sized by our forge planning from your drawing. Maximum single-piece capability is 8,000 kg.

Standards, testing and certification for Alloy 45 forgings

Fewer standards cover controlled-expansion alloys than cover stainless steels, and one of the most-cited specifications has recently changed status. That makes precise referencing on the purchase order more important, not less.

Table 8. Standards commonly applied to Alloy 45 forgings
Standard	Covers	Status / note
ASTM F30	Iron-nickel sealing alloys for glass sealing in electronic applications, covering chemistry, grain size, temper, surface and thermal expansion requirements	Withdrawn 2024 Still widely referenced on drawings. Cite a specific revision, e.g. ASTM F30-96(2017), so both sides know which limits apply.
ASTM B753	Thermostat component alloys, including low-expansion components of bimetal	Active The usual reference where the alloy is a bimetal component rather than a seal.
ASTM E228	Linear thermal expansion of solids by push-rod dilatometer	Active The test method to name whenever expansion is a contract property.
ASTM E112	Determining average grain size	Active Grain size is often specified for sealing surfaces.
ASTM A388	Ultrasonic examination of steel forgings	Active Our default UT acceptance practice.
EN 10228-3	Non-destructive testing of steel forgings, ultrasonic testing of ferritic and martensitic steel forgings	Active Preferred by European buyers.
SEP 1921	Ultrasonic testing of forgings, German steel-industry practice	Active Frequently specified on German and Central European drawings.
EN 10204 3.1	Inspection certificate issued by the manufacturer's authorised inspection representative	Active Standard on every Alloy 45 order we ship.
EN 10204 3.2	Inspection certificate countersigned by an independent third party	Active Available on request through Lloyd's, DNV, BV, ABS or TÜV.

Quality management and inspection

Jiangyin Jiangnan Metal Co., Ltd. operates an ISO 9001:2015 certified quality management system. Every Alloy 45 order passes six mandatory hold points at which production cannot continue without quality sign-off: raw-material chemistry verification, forging-temperature compliance, post-forging ultrasonic inspection, heat-treatment chart approval, mechanical and expansion test acceptance, and final dimensional plus surface inspection. Customer-witnessed hold points can be added at any of the six at no charge.

Any out-of-specification finding raises a formal non-conformance report within 24 hours, with root-cause analysis completed inside five working days. The customer receives the report and the proposed disposition, which may be rework, regrade, scrap or use-as-is under concession, before any action is taken. Material found to be non-conforming within six months of delivery, verified by independent third-party test, is replaced free of charge including freight. Shipping and test documentation is retained for ten years.

How to specify an Alloy 45 forging order

Most Alloy 45 disputes have one root cause: the order specified a chemistry when the customer needed an expansion coefficient. The seven steps below close that gap.

Name the grade and the standard"Alloy 45 (Fe-45%Ni controlled expansion)" plus the standard and revision, e.g. ASTM F30-96(2017) or ASTM B753, or attach your own chemistry sheet.
Specify the expansion itselfCoefficient value + temperature band + test method ASTM E228. This is the property that makes the part work.
Name the mating materialSoda-lime, soft lead glass, borosilicate, alumina, CFRP layup. Lets the mill sanity-check the nickel level before melting.
State the melting routeVIM+VAR for vacuum and hermetic seals with H/O/N limits; EAF+VOD+ESR for structural and tooling work.
Give form, size and stockRing, disc, shaft, sleeve, bar, block; finished dimensions; as-forged, rough or finish machined; machining allowance expected.
Define thermal processingAnneal, stress relief, and whether a stabilising thermal cycle is required for dimensional stability in service.
Define NDE and certificationUT acceptance to ASTM A388 / EN 10228-3 / SEP 1921, surface NDE, and EN 10204 3.1 or 3.2.

Ten mistakes engineers make when ordering Alloy 45

1. Specifying chemistry instead of expansion

A heat can sit inside the nickel band and still miss your expansion target. Fix: make the coefficient, its temperature band and ASTM E228 contract properties.

2. Quoting a CTE without a temperature band

"9 × 10⁻⁶/°C" means nothing on its own, because 20 to 100 °C and 30 to 300 °C give different numbers on the same bar. Fix: always write the band.

3. Running the part above the Curie point

Above about 440 °C Alloy 45 is just an ordinary austenitic alloy with roughly double the expansion. Fix: check with the service-temperature checker; move to Alloy 48 or 52 if needed.

4. Assuming Alloy 45 is the soda-lime grade

Soda-lime sits near 9.2; Alloy 48 or 52 usually matches it better. Fix: run the seal matcher before committing the design.

5. Confusing Alloy 45 with 45 Permalloy

Similar nickel level, completely different controlled property. One is specified for expansion, the other for magnetic permeability. Fix: state which property is controlled.

6. Skipping stress relief before finish machining

Machining stress relaxes later and the part drifts out of tolerance at the customer. Fix: rough → stress relieve → finish, always.

7. Ordering EAF material for a vacuum seal

Dissolved gas causes bubbles and leaks at the glass interface. Fix: specify VIM+VAR and state H, O and N limits for hermetic work.

8. Welding with a non-matched filler

The weld becomes a local expansion discontinuity and cracks the seal at the joint. Fix: matched Fe-Ni filler plus post-weld anneal.

9. Citing ASTM F30 without a revision

ASTM withdrew F30 in 2024, so "per ASTM F30" alone no longer points at a live document. Fix: cite ASTM F30-96(2017), or move the limits into your own sheet.

10. Sizing the section like steel

Alloy 45 has a modulus around 145 to 150 GPa against about 205 GPa for steel, so a like-for-like section deflects noticeably more. Fix: recheck stiffness as well as stress.

Alloy 45 drawing callout template

Copy this block into the material note on your drawing. It closes the ambiguities that cause most Alloy 45 re-quotes and rejections.

MATERIAL:      Alloy 45, iron-nickel controlled expansion alloy,
               nominally 45% Ni, balance Fe.
               Chemistry per ASTM F30-96(2017) [or ASTM B753] [or attached sheet Rev __].

EXPANSION:     Mean coefficient of linear thermal expansion
               ____ ± ____ x 10^-6 /degC over ____ to ____ degC,
               measured per ASTM E228 (push-rod dilatometer).
               Report the trace as an annex to the certificate.

MATING PART:   Seals / mates to ______________________ (name the glass or ceramic).

MELTING:       [ ] EAF + VOD + ESR    [ ] VIM + VAR (required for vacuum / hermetic service)
               Gas limits, where applicable: H __ ppm, O __ ppm, N __ ppm.

FORM:          ____________ (ring / disc / shaft / sleeve / bar / block)
               Dimensions per this drawing. Supplied [ ] as forged [ ] rough machined
               [ ] finish machined, machining allowance ____ mm per surface.

HEAT TREAT:    Anneal 830-870 degC. Stress relieve 500-600 degC after rough machining.
               [ ] Stabilising thermal cycle required, ____ cycles through ____ to ____ degC.

NDE:           UT per [ ] ASTM A388 Class __ [ ] EN 10228-3 Class __ [ ] SEP 1921 Class __
               Surface NDE: ____________

GRAIN SIZE:    ASTM E112 grain size ____ or finer (specify for sealing surfaces).

CERT:          EN 10204 [ ] 3.1  [ ] 3.2 witnessed by ____________
               Certificate to state actual heat analysis, heat treatment charts,
               UT report and dilatometer results.

MARKING:       Heat number, grade and drawing number, low-stress stamped or
               vibro-etched on a non-functional surface.

Fill the blanks before issuing. If you leave the expansion line empty, you have ordered a chemistry rather than a controlled-expansion part.

Alloy 45 RFQ generator

Build a complete enquiry with nothing missing, then copy it into an email or send it straight to WhatsApp.

Form required

Grade

Standard to certify against

Melting route

Dimensions

Quantity (pieces)

Expansion requirement

CTE value and band (if known)

Certification

Ultrasonic acceptance

Delivery term

Destination port / city

Your company (optional)

Application (helps us advise)

Where is Alloy 45 used?

Alloy 45 is specified wherever a metal part has to move the same amount as something that is not metal, or has to not move at all across a temperature swing. The forged forms we supply serve the larger end of that range.

Electronics & vacuum

Glass-to-metal seals and feed-throughs

Seal frames, housings, headers, eyelets and compression-seal bodies for soft-glass devices. Includes microelectronic packages, vacuum devices and lamp components. Forged rings and sleeves supplied as blanks for the sealing house to machine and pre-oxidise.

Aerospace tooling

Composite curing moulds and layup tooling

The largest single application for forged controlled-expansion alloy. A carbon-fibre part cured on a steel mould comes off the wrong size. A low-expansion mould avoids that. Rings, discs, blocks and near-net forgings for mould frames and backing structures.

Instruments & optics

Optical, laser and metrology structures

Spacers, mounts, tubes and support frames for telescopes, laser cavities, interferometers and measuring equipment, where a fraction of a micron of thermal drift is a measurement error.

Thermal controls

Thermostat bimetal components

The low-expansion leg of thermostatic bimetal strip and the machined components around it. This is the application behind the ASTM B753 reference. Bimetal thermostats, temperature regulators, circuit breakers.

RF & microwave

Cavity resonators, filters and shielding

Resonator bodies and filter housings whose tuned frequency depends on a dimension staying put, plus magnetic shielding enclosures where the alloy's ferromagnetic behaviour is itself useful.

Precision mechanical

Positioning devices, spacers, clock and instrument parts

Positioning hardware, precision spacers, balance wheels, pendulum components and other parts where dimensional repeatability across ambient temperature swings is the specification.

Additional forged shapes routinely supplied in Alloy 45 and its neighbouring grades include valve stems, valve seat rings, valve blocks and bodies, forged wheels, manifolds, rolls, spindles, gears, crankshafts, eccentric shafts, nozzles, bushings, tube sheets and seamless rolled rings. If the shape is not on this list, send the drawing. Open-die forging is a general-purpose process, and the limits are size and weight rather than geometry.

Glossary

Controlled-expansion alloy: An alloy whose coefficient of thermal expansion is deliberately set to a target value, rather than simply being low. Also called low-expansion or matched-expansion alloy.
Coefficient of thermal expansion (CTE): The fractional change in length per degree of temperature change, quoted in ×10⁻⁶/°C (equivalently ppm/°C). The value cannot be interpreted without the temperature band over which it was measured.
Mean vs instantaneous CTE: Mean CTE is the average over a stated band, which is what datasheets quote. Instantaneous CTE is the slope at one temperature, which is what a dilatometer trace shows and what reveals the Curie transition.
Curie temperature: The temperature at which a ferromagnetic material becomes paramagnetic. In Fe-Ni controlled-expansion alloys it is also the point where the expansion coefficient rises sharply, making it the functional service ceiling. Approximately 440 °C for Alloy 45.
Invar effect: The anomalously low thermal expansion of certain Fe-Ni alloys, caused by a magnetically driven volume effect that partly cancels normal thermal expansion below the Curie point.
Glass-to-metal seal: A hermetic joint made by wetting glass to a controlled oxide layer on a metal surface. A matched seal uses a metal with the same expansion as the glass; a compression seal deliberately uses a mismatch so the cooled glass is held in compression.
Pre-oxidation: A controlled thermal treatment that grows the adherent oxide layer the glass bonds to. Too little oxide and the glass will not wet; too much and the oxide spalls and the seal leaks.
Dilatometry / ASTM E228: Push-rod dilatometer measurement of linear thermal expansion. This is the standard test method for verifying that a heat meets its specified expansion coefficient.
ESR, electroslag remelting: A secondary remelting process that refines the solidification structure and reduces inclusions. Standard for large controlled-expansion forgings.
VIM + VAR: Vacuum induction melting followed by vacuum arc remelting. The clean, low-gas route specified where the part forms a hermetic seal or operates in vacuum.
Stabilising treatment: Thermal cycling through the intended service range before final machining, so residual dimensional movement happens on the shop floor rather than in service.
EN 10204 3.1 / 3.2: Inspection certificate types. 3.1 is issued by the manufacturer's authorised inspection representative; 3.2 is countersigned by an independent third party such as Lloyd's, DNV, BV, ABS or TÜV.

Frequently asked questions about Alloy 45

What is Alloy 45?

Alloy 45 is a controlled-expansion alloy containing nominally 45% nickel with the balance iron.

Its thermal expansion sits between Alloy 42 and Alloy 48 so it can be trimmed to match soft lead and soda-lime type glasses, and it stays approximately linear up to about 440 °C. That figure is its Curie temperature, above which the expansion coefficient rises sharply. It is used for glass-to-metal seals, thermostat bimetal low-expansion components, composite-curing tooling and precision fixtures. Jiangyin Jiangnan Metal Co., Ltd. forges Alloy 45 into seamless rolled rings, discs, shafts, sleeves, flanges, tube sheets and bars.

What is the chemical composition of Alloy 45?

Nominally 45% nickel, balance iron.

A typical works band is: nickel 45.0 nominal, carbon 0.05 max, manganese 0.80 max, silicon 0.30 max, chromium 0.10 max, aluminium 0.10 max, magnesium 0.05 max, phosphorus 0.025 max, sulfur 0.025 max, iron balance, with titanium and zirconium not deliberately added. Because it is a controlled-expansion alloy the nickel level is held far tighter than in a general engineering steel, and a shift of a few tenths of a percent measurably moves the expansion curve. See Table 2.

What is the thermal expansion coefficient of Alloy 45?

Typically in the region of 7.0 to 8.0 × 10⁻⁶ per °C over 30 to 300 °C.

That places it between Alloy 42 (about 5.3) and Alloy 48 (about 8.7). Published values differ between mills because the coefficient depends on the exact nickel level within the band and on prior thermal history, so expansion should always be a stated contract property verified by push-rod dilatometry per ASTM E228 rather than inferred from chemistry. Use the expansion explorer to see where it sits against other grades and against your glass.

What is the maximum service temperature of Alloy 45?

About 440 °C for controlled-expansion purposes.

That figure is the Curie temperature, where the alloy loses ferromagnetic ordering and the expansion coefficient rises abruptly toward normal austenitic values of roughly 14 to 16 × 10⁻⁶/°C. The alloy does not fail above 440 °C. It stops being a controlled-expansion alloy, so any sealing or dimensional function based on matched expansion is lost. For higher-temperature matched expansion, Alloy 48 (≈500 °C) and Alloy 52 (≈510 °C) have higher Curie points.

What is the difference between Alloy 42, Alloy 45 and Alloy 46?

Nickel content, which sets expansion and Curie temperature together.

Alloy 42 has about 42% nickel, the lowest expansion of the three at around 5.3 × 10⁻⁶/°C, and stays linear to roughly 380 °C. Alloy 45 has about 45% nickel, expansion around 7-8, and stays linear to roughly 440 °C. Alloy 46 has about 46% nickel, slightly higher expansion again, and a Curie point near 460 °C. You choose by the expansion you must match and the highest temperature the part will see. Low expansion and high temperature capability are not available in the same grade. See Table 5.

Is Alloy 45 the right grade for sealing to soda-lime glass?

Often not. Alloy 48 or Alloy 52 usually matches soda-lime glass more closely.

Soda-lime glass expands at roughly 9.2 × 10⁻⁶/°C over 0-300 °C, which is above the Alloy 45 range. Alloy 45 is the right choice when you need expansion in the 7-8 region, when you are matching a specific soft lead glass, when the design is already qualified on Alloy 45, or when you want more temperature headroom than Alloy 42 without moving further up the nickel scale. Jiangyin Jiangnan Metal forges every grade in the family, so ask us and we will say which one your glass actually needs.

Is Alloy 45 magnetic?

Yes, below about 440 °C.

Alloy 45 is ferromagnetic at room temperature and becomes paramagnetic above its Curie temperature. The magnetic transition and the expansion change occur together, which puts the practical service ceiling at the Curie point.

Does Alloy 45 have a UNS number?

Not one that every mill and buyer agrees on.

Fe-Ni controlled-expansion alloys in this family are normally ordered by nominal nickel content plus the governing standard, for example "Alloy 45 per ASTM F30-96(2017)" or "Alloy 45 per ASTM B753", rather than by a single universal number, and different suppliers use different designations for the same chemistry. State the chemistry band and the required expansion coefficient on the purchase order rather than relying on a trade name alone. See Table 1.

Which standards apply to Alloy 45?

Most commonly ASTM F30 for sealing alloys and ASTM B753 for thermostat component alloys.

Note that ASTM withdrew F30 in 2024, so a purchase order should cite a specific revision such as ASTM F30-96(2017) if it is used at all. Expansion is verified per ASTM E228, grain size per ASTM E112. Forgings are ultrasonically inspected to ASTM A388, EN 10228-3 or SEP 1921 and certified to EN 10204 3.1, or 3.2 with third-party witness. See Table 8.

What forged shapes and sizes are available in Alloy 45?

Rings to 2,500 mm OD, discs to Ø1,800 mm, shafts to 8 m, bars Ø25-500 mm, single pieces to 8,000 kg.

Jiangyin Jiangnan Metal Co., Ltd. supplies Alloy 45 as seamless rolled rings from 200 mm to 2,500 mm outside diameter, forged discs and hubs up to 1,800 mm diameter, forged shafts up to 8 m long, round bars from 25 mm to 500 mm diameter, plus sleeves, bushings, flanges, tube-sheet blanks, blocks and near-net-shape forgings to drawing.

What is the density of Alloy 45?

Approximately 8.17 g/cm³ (0.295 lb/in³) at room temperature.

Use this to convert drawing volume to finished forging weight when preparing an enquiry, then add 20-35% machining stock for the rough forging weight. The weight calculator above does both.

Can Alloy 45 be welded and machined?

Yes to both, subject to two cautions.

Alloy 45 welds readily by GTAW and electron-beam welding with matched Fe-Ni filler; because a weld is a local composition change it is also a local expansion change, so anneal after welding wherever matched expansion must hold across the joint, and keep sulfur and copper away from the joint to avoid hot cracking. Machining behaves like a soft austenitic stainless: gummy and work-hardening. Use sharp positive-rake carbide, rigid setups, constant feed with no dwell, and flood coolant. See machining and welding.

Why did my Alloy 45 part change size after machining?

Almost always residual stress that was never relieved.

Forging and rough machining both leave locked-in stress. When the finish cut removes material the stress redistributes and the part moves, sometimes days later. The fix is process order rather than material: forge, anneal, rough machine leaving stock, stress relieve at 500-600 °C, then finish machine. For parts that must hold a dimension in service, add a stabilising thermal cycle through the service range before the final cut.

What is the lead time and how do I get a quotation?

Typically 8-12 weeks; quotations issued within 24 hours.

Standard Alloy 45 rings, discs, shafts and bars ship in 8 to 12 weeks from order confirmation. Allow 12 to 16 weeks where VIM + VAR melting, dilatometer testing to ASTM E228, or EN 10204 3.2 third-party witnessed certification is required. Send a drawing or a size list to sales@steelforgepieces.com or use the RFQ generator above, and we will respond within 24 hours with price, lead time and confirmation of the applicable standards.

Request a quotation for Alloy 45 forgings

Send a drawing or a size list. We will come back within 24 hours with price, lead time, the melting route we recommend, and confirmation of which standards we can certify against. If a different grade in the family suits your application better, we will tell you that too.

Technical references

Property values, standards status and test-method references on this page are drawn from the published sources below. Certified values for any specific order are independent, measured on the delivered heat and traceable to calibrated equipment.

ASTM F30-96(2017), Standard Specification for Iron-Nickel Sealing Alloys, ASTM International, West Conshohocken, PA. Withdrawn 2024.
ASTM B753-19, Standard Specification for Thermostat Component Alloys, ASTM International.
ASTM E228-22, Standard Test Method for Linear Thermal Expansion of Solid Materials With a Push-Rod Dilatometer, ASTM International.
ASTM E112-13(2021), Standard Test Methods for Determining Average Grain Size, ASTM International.
ASTM A388/A388M-19, Standard Practice for Ultrasonic Examination of Steel Forgings, ASTM International.
ASTM F140, Standard Practice for Making Reference Glass-Metal Butt Seals and Testing for Expansion Characteristics by Polarimetric Methods, ASTM International.
EN 10228-3, Non-destructive testing of steel forgings, Part 3: Ultrasonic testing of ferritic or martensitic steel forgings, CEN, Brussels.
EN 10204:2004, Metallic products, types of inspection documents, CEN, Brussels.
SEP 1921, Ultrasonic Testing of Forgings, Stahl-Eisen-Prüfblatt, Verein Deutscher Eisenhüttenleute.
ASM Handbook, Volume 2: Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, ASM International, Materials Park, OH, chapter on controlled-expansion alloys.
ASM Specialty Handbook: Nickel, Cobalt, and Their Alloys, J.R. Davis (ed.), ASM International.
Guillaume, C.-É., Recherches sur les aciers au nickel, the original work on the Invar effect in iron-nickel alloys.
Wachtel, E. and Bach, H., Glass-Metal Seals, in Handbook of Glass Data / glass-to-metal sealing literature on matched and compression seals.
Nickel Institute technical literature on iron-nickel controlled-expansion and sealing alloys.

Standards are cited at the most recent revision known at the time of review. For procurement, always reference the revision in force at the contract date. All trademarks referenced on this site are the property of their respective owners; Jiangyin Jiangnan Metal Co., Ltd. produces generic chemistries and is not affiliated with, sponsored by, or endorsed by any trademark holder.

Cite this page

This page is maintained by the manufacturer named below and may be cited as a supplier-side technical reference for Alloy 45 controlled-expansion forgings. It was last reviewed on 12 August 2026.

Jiangyin Jiangnan Metal Co., Ltd. (2026). "Alloy 45 Forgings: Fe-45%Ni Controlled-Expansion Rings, Discs, Bars and Sleeves." Jiangyin, Jiangsu, China. https://www.steelforgepieces.com/Nickel-Alloy/Alloy-45.html (accessed 2026).

Manufacturer of record: Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory, No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China · 0086-189-2135-9659 · sales@steelforgepieces.com · ISO 9001:2015 · EN 10204 3.1 and 3.2 certification · forging since 2008 · exporting to 40+ countries.