UNS N05500 is an age-hardenable nickel-copper alloy containing 63.0 to 70.0 % nickel and 27.0 to 33.0 % copper, with 2.30 to 3.15 % aluminium and 0.35 to 0.85 % titanium added so it can be strengthened by precipitation of a gamma-prime Ni3(Al,Ti) phase. It is sold commercially as Monel® K-500 and is also designated Alloy K-500, Werkstoff 2.4375 and BS NA 18. Jiangyin Jiangnan Metal Co., Ltd. produces it as open-die forgings including rings, bars, flanges, discs and shafts.

Nickel-copper alloy · Open-die forgings

UNS N05500 Forgings (Monel K-500): Rings, Bars, Flanges and Shafts

UNS N05500 is an age-hardenable nickel-copper alloy containing 63.0 to 70.0 % nickel and 27.0 to 33.0 % copper, with 2.30 to 3.15 % aluminium and 0.35 to 0.85 % titanium added so the alloy can be precipitation strengthened. It is sold under the trade name Monel® K-500. After solution treatment and ageing, its 0.2 % yield strength is about three times that of solution-annealed Monel 400, while resistance to seawater and to sour, chloride-bearing media stays the same. The alloy is essentially non-magnetic at room temperature.

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. We manufacture UNS N05500 as seamless rolled rings, forged rings, round bars, flanges, discs, shafts, sleeves, bushings, tube sheets and valve components, in diameters from 80 mm to 6,000 mm and single-piece weights from 10 kg to 15,000 kg. Certification is issued to EN 10204 3.1 or 3.2. For enquiries call +86 189 2135 9659 or email sales@steelforgepieces.com.

Datasheet summary: UNS N05500

Nominal composition by weight. The aluminium and titanium addition is what makes the alloy age-hardenable.

UNS number: N05500
Trade name: Monel® K-500
Werkstoff / DIN: 2.4375
Density: 8.44 g/cm³ (0.305 lb/in³)
Melting range: 1315-1350 °C (2400-2460 °F)
Condition supplied: Solution treated and aged
Tensile strength: 965-1310 MPa (140-190 ksi)
0.2 % yield strength: 690-1035 MPa (100-150 ksi)
Hardness, aged: 27-38 HRC
Magnetic response: Non-magnetic, µ below 1.005
Melting route: ESR, or VIM + ESR + VAR
Certification: EN 10204 3.1 / 3.2

OverviewWhat is UNS N05500?

UNS N05500 is the Unified Numbering System designation for an age-hardenable nickel-copper alloy sold commercially as Monel® K-500. It uses the same nickel-copper base as Monel 400 (UNS N04400), with aluminium and titanium added. During ageing these elements form a fine gamma-prime Ni₃(Al,Ti) precipitate that raises strength without changing the corrosion behaviour of the alloy.

UNS N05500 resists flowing seawater, brackish water, hydrofluoric acid, sulphuric acid, alkalis and chloride stress-corrosion cracking. It remains non-magnetic at ambient temperature. These properties, together with its high strength, make the alloy a common choice for pump and propeller shafts, non-magnetic drill collars, valve stems and subsea fasteners in place of stainless steel.

Selecting UNS N05500 against other alloys

Compared with UNS N04400 (Monel 400): corrosion resistance is similar and yield strength is about three times higher. Welding and machining are more difficult.
Compared with duplex and super duplex stainless steel: better performance in reducing acids and in stagnant seawater under crevice conditions, and better galling and cavitation resistance on shafts.
Compared with UNS N07718 (Inconel 718): lower strength and a lower service ceiling of about 480 °C, but better performance in seawater and in hydrofluoric acid.

CompositionChemical composition of UNS N05500

Per ASTM B865, UNS N05500 is specified as nickel 63.0 to 70.0 %, copper 27.0 to 33.0 %, aluminium 2.30 to 3.15 % and titanium 0.35 to 0.85 %, with iron, manganese, carbon, silicon and sulphur controlled as residuals. Jiangyin Jiangnan Metal verifies chemistry twice: by optical emission spectrometry on the heat, and again by positive material identification on every finished forging.

UNS N05500 / Monel K-500 chemical composition, weight %
Element	Symbol	Min %	Max %	Function
Nickel	Ni	63.0	70.0	Matrix, corrosion resistance, toughness
Copper	Cu	27.0	33.0	Seawater and reducing-acid resistance
Aluminium	Al	2.30	3.15	Forms gamma-prime Ni3(Al,Ti) on ageing
Titanium	Ti	0.35	0.85	Co-precipitant, deoxidiser
Iron	Fe	-	2.0	Residual
Manganese	Mn	-	1.5	Residual, sulphur control
Carbon	C	-	0.25	Residual, kept low for toughness
Silicon	Si	-	0.50	Residual from deoxidation
Sulphur	S	-	0.010	Tramp element, reduced by ESR

Limits per ASTM B865. Aim chemistry can be tightened on request.

MechanicalMechanical properties of UNS N05500

In the hot-finished and aged condition, UNS N05500 forged bar and ring typically develops 965 to 1310 MPa (140 to 190 ksi) tensile strength, 690 to 1035 MPa (100 to 150 ksi) 0.2 % yield strength, 20 to 30 % elongation and 27 to 38 HRC. Values depend on section size, forging reduction and the ageing cycle. On heavy sections the achievable band should be agreed before manufacture.

Typical room-temperature mechanical properties by condition
Condition	Tensile, MPa (ksi)	0.2 % yield, MPa (ksi)	Elongation %	Hardness
Solution annealed, not aged	620-760 (90-110)	275-450 (40-65)	45-20	75-90 HRB
Hot-finished and aged bar, ring, forging	965-1310 (140-190)	690-1035 (100-150)	30-20	27-38 HRC
Cold-drawn and aged	1000-1310 (145-190)	725-1100 (105-160)	30-15	29-38 HRC
Sour-service capped NACE MR0175 / ISO 15156-3	as achieved	as achieved	-	35 HRC max

Typical values for guidance. Acceptance is against the ordered specification, tested per heat and heat-treatment lot.

Engineering note. Age-hardened nickel-copper alloy at high strength is susceptible to hydrogen embrittlement when cathodically protected in seawater, a mechanism associated with documented subsea fastener failures. Where UNS N05500 is used for cathodically protected bolting or highly stressed subsea components, hardness and yield strength should be capped rather than maximised. State the required cap on the order and it will be included in the manufacturing plan.

PhysicalPhysical properties of UNS N05500

UNS N05500 physical properties at 20 degrees Celsius unless stated
Property	Metric	Imperial
Density	8.44 g/cm³	0.305 lb/in³
Melting range	1315-1350 °C	2400-2460 °F
Modulus of elasticity, aged	179 GPa	26 x 10⁶ psi
Thermal conductivity	17.4 W/m·K	121 Btu·in/ft²·h·°F
Mean expansion, 20-100 °C	13.7 µm/m·K	7.6 µin/in·°F
Specific heat	419 J/kg·K	0.100 Btu/lb·°F
Electrical resistivity	615 nΩ·m	370 Ω·circ mil/ft
Relative magnetic permeability	Below 1.005, essentially non-magnetic. Curie point near -100 °C (-148 °F).
Practical max service temperature	about 480 °C	about 900 °F

Above about 480 degrees Celsius the ageing precipitate coarsens and strength falls. For sustained higher temperatures a Ni-Cr-Fe grade should be specified.

SpecificationsEquivalent grades and specifications

UNS N05500 is covered principally by ASTM B865 and AMS 4676. It appears in national systems as Werkstoff 2.4375, BS NA 18 and, in US government procurement, QQ-N-286, now SAE AMS-QQ-N-286.

UNS N05500 cross-reference
System	Designation	Scope
UNS (USA)	N05500	Alloy designation
Trade name	Monel® K-500	Special Metals Corporation
ASTM	B865	Rod, bar, wire and forging stock
SAE / AMS	AMS 4676	Bars, forgings and rings
US federal	SAE AMS-QQ-N-286	Bar, plate, sheet, forgings, wire
Germany	W.-Nr. 2.4375 (DIN 17743 / 17752)	NiCu30Al
United Kingdom	BS NA 18	Nickel-copper, age-hardening
Sour service	NACE MR0175 / ISO 15156-3	Listed with hardness restrictions
Ultrasonic testing	EN 10228-3, SEP 1921, ASTM A388	Volumetric examination of forgings
Certification	EN 10204 3.1 / 3.2	Mill certificate, third-party witness

Cross-references are for guidance only. Equivalence between systems is never exact. Order against a single governing specification.

Product rangeUNS N05500 forged products

Jiangyin Jiangnan Metal Co., Ltd. produces UNS N05500 as open-die forgings and seamless rolled rings, made to drawing, in diameters from 80 mm to 6,000 mm, lengths up to 12,000 mm and single-piece weights from 10 kg to 15,000 kg. All items listed below are forged rather than cast or fabricated, so grain flow follows the part contour.

UNS N05500 forged product range and size capability
Forged form	Size range	Single-piece weight
Seamless rolled rings	OD 80-6,000 mm, wall from 20 mm, height to 1,000 mm	10-15,000 kg
Forged rings	OD 80-6,000 mm, to drawing	10-15,000 kg
Forged round bars	dia. 80-1,200 mm, length to 12,000 mm	to 15,000 kg
Forged discs, disks and blanks	dia. 100-3,000 mm, thickness to 800 mm	to 15,000 kg
Forged flanges	DN 15 to DN 1,200, ASME B16.5 / B16.47, Class 150-2500, WN SO BL LJ	to drawing
Forged shafts, spindles, crankshafts	dia. 80-1,200 mm, length to 12,000 mm	to 15,000 kg
Forged sleeves and bushings	OD 100-2,000 mm, to drawing	to 15,000 kg
Forged tube sheets	dia. to 3,000 mm, thickness to 500 mm	to 15,000 kg
Forged hollow bars and tubes	OD 100-2,000 mm, ID from 60 mm	to 15,000 kg
Forged blocks, valve bodies, nozzles	to drawing	to 15,000 kg
Forged gear blanks and rolls	dia. 150-3,000 mm	to 15,000 kg

Supplied as-forged with machining allowance, rough machined, or finish machined to drawing.

ProcessProduction route for UNS N05500 forgings

Nickel-copper alloy has a narrow hot-working window, work-hardens quickly, and becomes hot-short if overheated because of its aluminium and titanium content. The route below is set up to control these conditions.

Melting and refiningElectric arc furnace melt with vacuum oxygen decarburisation refining. Electroslag remelting is applied where low sulphur, reduced segregation and a clean inclusion population are required for Class 3 ultrasonic acceptance. VIM + ESR + VAR is available where the specification calls for it.
Ingot conditioning and homogenisationSurface conditioning, followed by a homogenising soak to even out aluminium and titanium distribution before the first blow.
Open-die forgingHeating to 1,065-1,120 °C (1,950-2,050 °F). Heavy reduction is taken above 980 °C and finishing passes down to about 870 °C, with reheats as required. Total forging ratio is normally 4:1 or greater. Equipment includes 1, 3, 6 and 9 ton hammers and a 4,500 ton hydraulic press.
Ring rollingPierced blanks are expanded on 3-metre and 6-metre ring mills to produce circumferential grain flow, which gives better performance in pressure-containing joints than a ring cut from plate.
Solution treatment871-899 °C (1,600-1,650 °F), soaked to section, then rapidly cooled to hold the aluminium and titanium in solution.
Age hardening580-595 °C (1,080-1,100 °F) held about 16 hours, followed by controlled furnace cooling. The cycle is set to the hardness band stated on the order.
MachiningRough or finish machining on CNC lathes and boring mills. Low surface speed and positive rake tooling are used because the alloy work-hardens readily.
Testing and documentationChemistry, mechanical test, hardness, ultrasonic and surface NDT, dimensional report, then marking, preservation and packing.

Heat treatmentUNS N05500 heat treatment cycle

Typical solution and ageing practice for UNS N05500 forgings
Stage	Temperature	Hold	Cooling
Hot working	1,065-1,120 °C (1,950-2,050 °F)	To section	Reheat as required, finish above 870 °C
Solution anneal	871-899 °C (1,600-1,650 °F)	1 h per 25 mm	Water quench or rapid air cool
Age harden	580-595 °C (1,080-1,100 °F)	about 16 h	Furnace cool about 8 °C/h to 480 °C, then air cool
Age, cold-worked stock	525-580 °C (980-1,080 °F)	6-16 h	Shorter cycle to avoid over-ageing
Stress relief after machining	about 540 °C (1,000 °F)	1-3 h	Air cool

Cycles are adjusted to section size and to the hardness or strength band on the order.

InspectionTesting, inspection and certification

Chemistry

OES and PMI

Optical emission spectrometry on the heat, plus positive material identification by XRF on 100 % of finished forgings before shipment.

Mechanical

Tensile, hardness, impact

Room-temperature tensile per heat and heat-treatment lot, Rockwell C hardness survey, and Charpy V-notch including sub-zero test temperatures when specified.

Volumetric NDT

Ultrasonic examination

UT to EN 10228-3, SEP 1921 including Class 3, or ASTM A388. The acceptance class is stated on the order and recorded on the certificate.

Surface NDT

Liquid penetrant

PT to ASTM E165 or EN 10228-2. Magnetic particle inspection is not applicable because the alloy is non-magnetic.

Metallurgical

Grain size and microstructure

ASTM E112 grain size, macro-etch for flow lines and segregation, and intergranular corrosion testing where the specification requires it.

Documents

EN 10204 3.1 and 3.2

Mill certificates as standard. 3.2 certificates witnessed by TUV, BV, SGS, Lloyd's Register or DNV on request, with full heat and NDT traceability.

ApplicationsApplications for UNS N05500 forgings

UNS N05500 is specified where a component must carry high stress in seawater or in sour, chloride-bearing service and must remain non-magnetic. Typical forged components by industry are listed below.

UNS N05500 forgings by industry and component
Industry	Typical forged components
Marine and subsea	Propeller and pump shafts, seawater pump sleeves and wear rings, valve stems, subsea fasteners and studs, tidal-water hardware
Oil and gas, drilling	Non-magnetic drill collars, MWD and LWD instrument housings and sleeves, wellhead and Christmas tree components, safety valve parts, sour-service trim
Valves and pumps	Valve stems, seats and seat rings, plugs, bodies and blocks for ball, gate, globe, check and plug valves. Plunger pump rods and chemical pump shafts
Chemical processing	Pump shafts and impellers, crystalliser components, heat exchanger tube sheets, forged nozzles, reactor internals for hydrofluoric and sulphuric acid service
Pressure equipment	Forged flanges, tube sheets, shells and heads for pressure vessels, air receivers and shell-and-tube heat exchangers. Column, tower and silo fittings
Pulp and paper	Doctor blades, scrapers, forged rolls and shafts in bleach and chloride environments
Instrumentation	Non-magnetic housings, springs, retaining rings and precision sleeves
Heavy machinery	Eccentric shafts, forged wheels, manifolds, crankshafts and gear blanks for shipbuilding and process modules

ComparisonUNS N05500 compared with Monel 400 and Inconel 718

UNS N05500 is selected when Monel 400 corrosion resistance is required at higher strength. UNS N04400 is selected when the part must be welded. UNS N07718 is selected when service temperature rather than seawater is the governing condition.

Comparison of UNS N05500 with UNS N04400 and UNS N07718
Attribute	UNS N05500 Monel K-500	UNS N04400 Monel 400	UNS N07718 Inconel 718
Alloy system	Age-hardenable Ni-Cu	Solid-solution Ni-Cu	Age-hardenable Ni-Cr-Fe
Nickel, %	63.0-70.0	63.0 min	50.0-55.0
Copper, %	27.0-33.0	28.0-34.0	0.30 max
0.2 % yield, MPa	690-1035	170-345	1035 min
Tensile, MPa	965-1310	480-620	1240 min
Hardness	27-38 HRC	60-80 HRB	331-444 HBW
Magnetic at 20 °C	No	No	No
Seawater resistance	Excellent	Excellent	Good
Max service temperature	about 480 °C	about 540 °C	about 700 °C
Weldability	Difficult. Anneal, weld, then re-age	Good	Good, with post-weld treatment
Typical use	High-strength marine shafts, drill collars, valve stems	Seawater piping, heat exchangers, weldments	Hot, highly stressed components

ManufacturerAbout Jiangyin Jiangnan Metal Co., Ltd.

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. The works employs 460 people, including 9 senior engineers and 32 intermediate engineers.

Forging equipment includes 1 ton, 3 ton, 6 ton and 9 ton open-die forging hammers, a 4,500 ton hydraulic press, and 3-metre and 6-metre seamless ring rolling mills. Forgings are produced from 80 mm to 6,000 mm in diameter, from 10 kg to 15,000 kg in weight, and up to 12,000 mm long. Melting routes are ESR, or VIM + ESR + VAR where the specification requires it.

Materials cover carbon steel, alloy steel, tool steel, stainless steel and nickel alloys, including the nickel-copper, Inconel, Incoloy and Hastelloy ranges. Raw material supply, forging, heat treatment, machining, testing and inspection are all carried out in house. Jiangyin is about 150 km from the Port of Shanghai.

What we do

Open-die forging to drawing

Free-forged and ring-rolled parts made from your drawing or size list. No tooling charge and single pieces accepted.

Materials

Nickel alloys and steels

UNS N05500, Monel 400, Inconel 600, 601, 617, 625, 690, 718, 725 and X-750, Incoloy 800, 825, 925 and 945, Hastelloy B and C series, 17-4PH, 15-5PH, PH13-8Mo, and carbon, alloy and tool steels.

Quality

Certified and traceable

EN 10204 3.1 as standard, 3.2 with third-party witness on request, with heat number traceability from ingot to packing list.

Export

Worldwide supply

Regular shipments to the USA, Germany, Italy, the UK, the Netherlands, Norway, the UAE, India, Singapore and Brazil.

ReferenceJiangyin Jiangnan Metal Co., Ltd. "UNS N05500 Forgings (Monel K-500): Rings, Bars, Flanges and Shafts." steelforgepieces.com, last reviewed 29 August 2026. http://www.steelforgepieces.com/Nickel-Alloy/UNS-N05500.html

Manufacturer of recordJiangyin Jiangnan Metal Co., Ltd., No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Tel +86 189 2135 9659. Email sales@steelforgepieces.com

FAQFrequently asked questions about UNS N05500

What is UNS N05500?

UNS N05500 is an age-hardenable nickel-copper alloy containing 63.0 to 70.0 % nickel and 27.0 to 33.0 % copper, with 2.30 to 3.15 % aluminium and 0.35 to 0.85 % titanium added so it can be strengthened by precipitation of a gamma-prime Ni₃(Al,Ti) phase. It is sold commercially as Monel® K-500 and is also designated Alloy K-500, Werkstoff 2.4375 and BS NA 18. Jiangyin Jiangnan Metal Co., Ltd. produces it as open-die forgings including rings, bars, flanges, discs and shafts.

Is UNS N05500 the same as Monel K-500?

Yes. UNS N05500 is the UNS designation for the alloy marketed under the trade name Monel® K-500. The same material also appears as Alloy K-500, Nickel Alloy K500, Werkstoff 2.4375, BS NA 18 and QQ-N-286. Chemistry and property requirements are set by ASTM B865 and AMS 4676.

What is the chemical composition of UNS N05500?

Nickel 63.0 to 70.0 %, copper 27.0 to 33.0 %, aluminium 2.30 to 3.15 %, titanium 0.35 to 0.85 %, carbon 0.25 % max, manganese 1.5 % max, iron 2.0 % max, silicon 0.50 % max and sulphur 0.010 % max, by weight, per ASTM B865.

What is the difference between UNS N05500 and Monel 400?

Both are nickel-copper alloys with similar corrosion resistance. UNS N05500 adds aluminium and titanium so it can be age hardened. After solution treatment and ageing it reaches about 690 to 1035 MPa yield strength and 27 to 38 HRC, roughly three times the yield strength of solution-annealed Monel 400. Monel 400 (UNS N04400) is easier to weld and machine and is used where strength is not the limiting factor.

Is UNS N05500 magnetic?

No, not at room temperature. Relative magnetic permeability is typically below 1.005, and the Curie temperature is near -100 °C (-148 °F), so the alloy becomes weakly ferromagnetic only at cryogenic temperatures. This is one reason it is used for non-magnetic drill collars and MWD instrument housings in directional drilling.

What heat treatment does UNS N05500 need?

Solution anneal at 871 to 899 °C (1,600 to 1,650 °F) followed by rapid cooling, then age harden at 580 to 595 °C (1,080 to 1,100 °F) for about 16 hours with a controlled furnace cool. Jiangyin Jiangnan Metal performs solution treatment and ageing in sequence and sets the ageing cycle to the hardness or strength band on the order.

Can UNS N05500 be used in sour service under NACE MR0175 / ISO 15156?

UNS N05500 is listed in NACE MR0175 / ISO 15156-3 for certain components subject to hardness limits, commonly 35 HRC maximum. Separately, age-hardened nickel-copper alloy at high strength is susceptible to hydrogen embrittlement under cathodic protection in seawater, so subsea bolting and highly stressed parts should be reviewed against both hardness and strength caps. State the required condition on the enquiry and it will be built into the manufacturing plan.

Which standards cover UNS N05500 forgings?

ASTM B865 for rod, bar and wire. AMS 4676 for bars, forgings and rings. SAE AMS-QQ-N-286, formerly QQ-N-286. DIN 17743 / 17752 for Werkstoff 2.4375. Ultrasonic examination is normally to EN 10228-3, SEP 1921 or ASTM A388, with certificates to EN 10204 3.1 or 3.2.

What sizes of UNS N05500 forged rings can you produce?

Seamless rolled rings from 80 mm to 6,000 mm outside diameter on 3-metre and 6-metre ring rolling mills, in single-piece weights from 10 kg to 15,000 kg. Forged bars and shafts are produced up to 12,000 mm long and up to 1,200 mm in diameter.

Is UNS N05500 weldable?

It is weldable but regarded as difficult. Weld in the solution-annealed condition using a nickel-copper filler such as AWS ERNiCu-7. The age-hardened condition is prone to heat-affected-zone cracking. Re-solution treat and re-age after welding to restore properties. Where a welded joint is unavoidable in a highly stressed part, UNS N04400 is normally specified instead.

What is the minimum order quantity and lead time?

Single pieces are accepted and there is no fixed minimum order quantity for UNS N05500 forgings. Typical lead time is 25 to 45 days from drawing approval, depending on piece weight, melting route and the extent of machining and testing. Send a drawing or size list for a firm date.

Who supplies UNS N05500 open-die forgings from China?

Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, manufactures UNS N05500 (Monel K-500) forged rings, seamless rolled rings, bars, flanges, discs, shafts, sleeves, bushings and tube sheets. Contact +86 189 2135 9659 or sales@steelforgepieces.com.

Page last reviewed 29 August 2026 by the technical sales department, Jiangyin Jiangnan Metal Co., Ltd.