Alloy 400 / Monel 400 / UNS N04400 Forging Parts: Nickel-Copper Forgings for Seawater, HF Acid and Caustic Service
Alloy 400 (UNS N04400, DIN 2.4360 / NiCu30Fe, widely known by the trademark Monel® 400) is a single-phase nickel-copper alloy of roughly 63–70 % nickel and 28–34 % copper. It is the reference material for flowing seawater, hydrofluoric acid and caustic soda, it is effectively immune to chloride stress-corrosion cracking, and it retains ductility from cryogenic temperatures up to about 480–540 °C. Because it is a solid-solution alloy it cannot be age hardened. Strength comes only from cold work.
Jiangyin Jiangnan Metal Co., Ltd. is an independent open-die forging factory in Jiangyin, Jiangsu, China that manufactures UNS N04400 forgings to ASTM B564, ASTM B164 and NACE MR0175 / ISO 15156: seamless rolled rings to 2,500 mm OD, forged discs to 1,800 mm diameter, shafts to 8 m, bar from 25–500 mm Ø, and single-piece weights to 8,000 kg, supplied annealed with EN 10204 3.1 certification as standard, 3.2 third-party witnessed on request. Quotations are issued within 24 hours to sales@steelforgepieces.com or 0086-189-2135-9659.
- UNS
- N04400Ni-Cu solid solution
- Werkstoff
- 2.4360NiCu30Fe
- Density
- 8.80g/cm³
- UTS annealed
- ≥480MPa (70 ksi) min
- Yield 0.2 %
- ≥170MPa (25 ksi) min
- Max service
- ~540°C in air
- NACE limit
- 35HRC max
- Age hardenable
- Nouse K-500 instead
What is Alloy 400 / Monel 400 / UNS N04400?
Alloy 400 is a binary nickel-copper alloy, nominally 66 % nickel and 31.5 % copper with a small iron and manganese addition, that forms a single-phase solid solution across its whole composition range. Nickel and copper are mutually soluble in all proportions, so there is no second phase to precipitate, no sensitisation window and no carbide network to control. That single fact governs almost everything an engineer needs to know about the grade: it is unusually tolerant of heat-treatment mistakes, it welds without post-weld heat treatment, and it cannot be hardened by any thermal cycle.
Commercially the alloy dates to 1906, when it was smelted directly from a Sudbury nickel-copper ore whose natural ratio happened to be close to the ideal, and it remains the oldest nickel alloy still in large-scale industrial use. Its combination of properties has never been bettered for three specific environments: flowing seawater, hydrofluoric acid, and hot caustic soda. Those three account for the majority of the UNS N04400 forgings we ship.
Alloy 400 sits high enough in the galvanic series to resist general corrosion in seawater, yet it contains no chromium, so there is no passive film to be broken down by chlorides. The practical consequence is that Alloy 400 is effectively immune to chloride stress-corrosion cracking, the failure mode that destroys 304 and 316 stainless in warm chloride service. Its corrosion rate in flowing seawater is typically under 0.025 mm/year, and unlike copper-nickel alloys it tolerates high flow velocities without erosion-corrosion.
The compensating weakness follows from the same chemistry. Without chromium, Alloy 400 has no resistance to oxidising conditions. It fails rapidly in nitric acid, in oxidising salts such as ferric chloride and cupric chloride, and in aerated acids generally. It also suffers crevice and pitting attack in stagnant seawater under fouling deposits, which is why marine designers specify continuous flow or periodic flushing. Understanding this oxidising / reducing split is the single most useful mental model for the grade: Alloy 400 is outstanding in reducing conditions and poor in oxidising ones.
Two further characteristics matter in design. First, the alloy is not age hardenable, a point on which a great deal of published web content is simply wrong. Solution treatment plus ageing belongs to Alloy K-500 (UNS N05500), which adds aluminium and titanium so that γ′ can precipitate. Alloy 400 is strengthened by cold work alone, and the only thermal treatments that apply are annealing and stress relief. Second, its Curie temperature falls close to room temperature, so whether a given heat is magnetic depends on its exact iron content and its temperature, a detail that regularly surprises buyers specifying non-magnetic hardware.
What Forged Products Are Available in Alloy 400 / UNS N04400?
Jiangyin Jiangnan Metal manufactures UNS N04400 through three forging routes chosen by geometry and quantity. Open-die forging covers long shafts, blocks and large discs: the route for pump shafts, valve blocks and tube sheets. Seamless hot ring rolling produces forged rings from 200 mm to 2,500 mm outside diameter, the most common form for seawater valve bodies, pump casings and flange blanks. Upset forging handles short, large-section hubs and stub ends. Alloy 400 forges well but has a narrow finishing window and a severe sulfur sensitivity, both covered under forging practice below.
Seamless rolled rings
200–2,500 mm OD, rectangular, contoured or T-section. Seawater valve bodies, pump casings, flange blanks.
Forged shafts & spindles
To 8 m length. Seawater and chemical pump shafts, agitator shafts, propeller shafts.
Forged flanges
ASTM B564 flanges to ASME B16.5 and B16.47, weld necks, blinds, orifice and long weld necks for HF alkylation.
Tube sheets & discs
Discs and tube sheets to 1,800 mm diameter, drilled or blank, for shell-and-tube exchangers and condensers.
Valve bodies, bonnets, stems, seat rings
Ball, gate, globe, check and plug valve components for seawater, HF and caustic duty.
Bar, blocks, sleeves, bushings
Round and flat bar 25–500 mm Ø per ASTM B164, forged blocks, sleeves, bushings and near-net blanks.
| Part | Size as forged | Condition and duty | Specification |
|---|---|---|---|
| Seamless rolled ring | OD 900 mm × 110 mm wall | Annealed. Seawater valve body blank | UNS N04400 · ASTM B564 |
| Forged pump shaft | Ø160 mm × 3.2 m | Annealed, rough machined. Seawater lift pump | UNS N04400 · ASTM B164 |
| Forged weld neck flange | ASME B16.5 Class 300 | Annealed and hardness mapped. HF alkylation duty | ASTM B564 · UNS N04400 |
| Forged tube sheet | Ø1,400 mm × 130 mm | Ultrasonically tested before drilling | DIN 2.4360 · NiCu30Fe |
What Are the Equivalents of Alloy 400? (UNS N04400, 2.4360, NA13, NW4400)
Alloy 400 appears on drawings under at least a dozen names. Every designation in the table below refers to the same nickel-copper chemistry, and Jiangyin Jiangnan Metal accepts purchase orders under all of them, issuing a multi-designation material test certificate that lists each specification the heat satisfies.
| Standard / body | Designation | Scope & notes |
|---|---|---|
| Brand (trademark) | Monel® 400 | Registered trademark of Special Metals Corporation. We do not sell under this name; we ship the generic equivalents below. |
| Brand (trademark) | Nicorros®, Nickelvac® 400 | VDM Metals and other producers' brand names for the same chemistry. |
| USA · UNS | N04400 | Generic Unified Numbering System designation, the safest way to specify |
| USA · ASTM (forgings) | ASTM B564 | Nickel alloy forgings, including forged flanges and fittings. Our primary product specification |
| USA · ASTM (bar) | ASTM B164 | Ni-Cu rod, bar and wire. Includes free-machining grade N04405 |
| USA · ASTM (plate) | ASTM B127 | Ni-Cu plate, sheet and strip |
| USA · ASTM (pipe) | ASTM B165 / B725 / B730 | Seamless and welded Ni-Cu pipe and tube |
| USA · ASTM (fittings) | ASTM B366 | Wrought Ni-Cu fittings |
| USA · ASME BPVC | SB-564 / SB-164 / SB-127 | Pressure-vessel code equivalents, Section II Part B; allowable stresses to 425 °C |
| USA · AMS | AMS 4675 | Ni-Cu bars, forgings and rings, annealed |
| USA · Military | QQ-N-281 | Legacy US federal spec, Class A (annealed) / Class B (stress relieved); still cited by navy drawings |
| EU · DIN / EN | 2.4360 · NiCu30Fe | Werkstoff number and EN name; DIN 17750–17754 product forms |
| UK · BS | NA13 | BS 3072–3076 series |
| France · AFNOR | NU-30 | NF A 54 series |
| Japan · JIS | NW4400 | JIS H 4551 / H 4552 (also written NCuF) |
| China · GB/T | NCu30 (NCu28-2.5-1.5) | GB/T 15007 Chinese designation for the Ni-Cu 400 chemistry |
| Sour service | NACE MR0175 / ISO 15156-3 | N04400 accepted in annealed or hot-worked condition, 35 HRC maximum |
Multi-standard designation lookup
Type any name (Alloy 400, Monel, N04400, 2.4360, NiCu30Fe, NA13, NW4400, B564) and see every equivalent instantly.
What Is the Chemical Composition of Alloy 400 / UNS N04400?
The composition below is per ASTM B564 and ASTM B164 and is identical in ASME SB-564. Note the unusual form of the specification: only nickel and copper are controlled to a range, and nickel is quoted as a minimum with cobalt counted in. Because the balance is copper, a typical mill analysis lands near 66 % Ni and 31.5 % Cu.
| Element | Min | Max | Typical | Metallurgical role |
|---|---|---|---|---|
| Nickel + Cobalt (Ni + Co) | 63.0 | – | 66 | Matrix. Provides resistance to caustic, HF and reducing acids |
| Copper (Cu) | 28.0 | 34.0 | 31.5 | Solid-solution partner; the source of seawater and HF resistance |
| Iron (Fe) | – | 2.50 | 1.6 | Residual from raw material; raises the Curie temperature |
| Manganese (Mn) | – | 2.00 | 1.0 | Deoxidiser; combines with residual sulfur |
| Carbon (C) | – | 0.30 | 0.15 | Residual. No hardening effect; carbides do not strengthen this matrix |
| Silicon (Si) | – | 0.50 | 0.15 | Deoxidiser |
| Sulfur (S) | – | 0.024 | 0.008 | Impurity, kept very low because sulfur embrittles the alloy at forging temperature |
ASTM B164 also covers UNS N04405, which is the same alloy with sulfur deliberately raised to 0.025–0.060 % to break up chips. Machinability improves substantially, but the sulfide stringers reduce hot workability and corrosion performance, so N04405 is supplied as bar for machined parts and is not used for forgings or for welded assemblies. If a drawing calls for "Monel 405", specify N04405 bar. Do not substitute N04400 without telling the machine shop, and never substitute N04405 into a forging.
What Are the Mechanical Properties of Alloy 400 Forgings?
Alloy 400 has modest strength but very high ductility and toughness. The specified minima are what a certificate must show; the typical values are what a well-processed forging actually delivers. Cold work is the only way to raise strength, and it must be traded against corrosion performance, because cold-worked material is more susceptible to stress-corrosion cracking in the few media that attack this alloy.
| Condition | Tensile strength | Yield 0.2 % | Elongation | Hardness | Use |
|---|---|---|---|---|---|
| Annealed, minimum per ASTM B564 | 480 MPa 70 ksi | 170 MPa 25 ksi | 35 % | ≤ 75 HRB | Standard for all corrosion service |
| Annealed, typical | 517–620 MPa 75–90 ksi | 172–345 MPa 25–50 ksi | 35–60 % | 60–80 HRB | What a normal heat delivers |
| Hot-finished / as-forged | 550–690 MPa 80–100 ksi | 275–480 MPa 40–70 ksi | 45–30 % | 75–95 HRB | Where higher strength is acceptable |
| Cold-drawn, stress relieved | 580–830 MPa 85–120 ksi | 380–690 MPa 55–100 ksi | 30–15 % | 85–100 HRB | Small bar, fasteners, shafting |
| Age hardened | Not applicable. Alloy 400 cannot be age hardened | Use Alloy K-500 | |||
Values for forgings and bar up to 150 mm section. Impact toughness is high in all conditions and, unusually, increases as temperature falls. Alloy 400 has no ductile-to-brittle transition and is routinely used to −250 °C. Charpy V-notch of annealed material is typically 200–270 J at room temperature.
A large amount of online material, including datasheets copied from one supplier to another, states that Alloy 400 can be "solution treated and aged". It cannot. Nickel and copper form a continuous solid solution with no precipitating phase, so there is nothing to age. A purchase order calling for aged UNS N04400 cannot be fulfilled by anyone and will come back as a technical query. If your design needs 3× the yield strength with the same corrosion resistance, the correct grade is Alloy K-500 / UNS N05500, which contains ~2.7 % Al and ~0.6 % Ti and is aged around 595 °C.
Elevated-temperature strength
Alloy 400 loses strength gradually and predictably with temperature. ASME Section VIII Division 1 lists allowable stresses for N04400 to 425 °C (800 °F); above that, creep governs and the alloy is rarely used for pressure parts.
| Temperature | Tensile strength | Yield 0.2 % | Elongation |
|---|---|---|---|
| 20 °C / 68 °F | 550 MPa | 240 MPa | 48 % |
| 200 °C / 392 °F | 520 MPa | 205 MPa | 47 % |
| 300 °C / 572 °F | 505 MPa | 195 MPa | 46 % |
| 400 °C / 752 °F | 480 MPa | 185 MPa | 44 % |
| 500 °C / 932 °F | 415 MPa | 180 MPa | 42 % |
| 600 °C / 1112 °F | 290 MPa | 170 MPa | 45 % |
| −196 °C / −321 °F | 760 MPa | 300 MPa | 55 % |
Typical values for annealed hot-finished material, indicative only. Use ASME Section II Part D for code allowable stresses. Note the cryogenic row: both strength and ductility rise as temperature falls, which is why Alloy 400 is a standard cryogenic valve and pump material.
What Are the Physical Properties of Alloy 400?
| Property | Value | Unit / condition |
|---|---|---|
| Density | 8.80 | g/cm³ (0.318 lb/in³) at 20 °C |
| Melting range | 1300–1350 | °C (2370–2460 °F) |
| Modulus of elasticity | 179 | GPa (26 × 10⁶ psi), annealed |
| Shear modulus | 66 | GPa |
| Poisson's ratio | 0.32 | – |
| Coefficient of thermal expansion | 13.9 / 14.8 / 15.7 | ×10⁻⁶ /°C for 20–100 / 20–300 / 20–500 °C |
| Thermal conductivity | 21.8 | W/m·K at 20 °C |
| Specific heat | 427 | J/kg·K at 20 °C |
| Electrical resistivity | 0.547 | µΩ·m at 20 °C |
| Curie temperature | 20–50 | °C, varies with iron content; see note below |
| Relative permeability | ≈ 1.0 to >100 | Depends on temperature relative to the Curie point |
The Curie temperature of UNS N04400 sits between roughly 20 °C and 50 °C, moving with iron and manganese content within the specification band. A heat at the low-iron end may be essentially non-magnetic at 25 °C; a heat at the high-iron end will be weakly ferromagnetic at the same temperature and become non-magnetic only when warmed slightly. Never assume Alloy 400 is non-magnetic. If your application requires guaranteed low permeability (instrument housings, sensor bodies, magnetic-particle-free assemblies), state the maximum permeability and the temperature at which it must be met on the purchase order, and we will select and verify the heat. Where a genuinely non-magnetic nickel alloy is needed regardless of temperature, Inconel 625 or a fully austenitic stainless such as Nitronic 50 is the safer choice.
How Corrosion-Resistant Is Alloy 400 in Seawater, HF Acid and Caustic?
Alloy 400 has no chromium and therefore no passive oxide film. It resists corrosion the way a noble metal does, by being thermodynamically stable in reducing conditions, rather than the way stainless steel does, by repassivating. Every prediction about this alloy follows from that distinction, summarised in one rule: excellent in reducing environments, poor in oxidising ones. An oxidising contaminant as small as a few hundred ppm of ferric ion can turn a service that Alloy 400 handles perfectly into one that consumes it in months.
| Medium | Rating | Conditions and limits |
|---|---|---|
| Seawater, flowing | A | Typically <0.025 mm/year. The classic application. Tolerates high velocity better than any copper alloy |
| Seawater, stagnant | C | Crevice and pitting attack under deposits and biofouling. Design for continuous flow or periodic flushing |
| Brackish & brine, non-oxidising | A | Excellent across concentration and temperature. No chloride SCC |
| Hydrofluoric acid (HF), non-aerated | A | The reference material. All concentrations to the boiling point. Used throughout HF alkylation units |
| Hydrofluoric acid, aerated or vapour + O₂ | B | Rate rises with aeration. Stress-corrosion cracking reported in moist aerated HF vapour; specify stress-relieved or annealed parts |
| Sodium hydroxide (caustic soda) | A | All concentrations to ~boiling. One of the best commercial materials for caustic evaporators |
| Caustic, concentrated and hot (>300 °C) | B | Caustic SCC possible in highly stressed parts. Stress-relieve at 540–590 °C after fabrication |
| Sulfuric acid <85 %, non-aerated, ≤ 60 °C | B | Acceptable when air and oxidising contaminants are excluded. Aeration degrades it sharply |
| Sulfuric acid >85 % or aerated | C | Not recommended |
| Hydrochloric acid, dilute, cold, non-aerated | B | Useful to roughly 10 % at ambient temperature with oxygen excluded. Rate climbs quickly with heat or aeration |
| Hydrochloric acid, hot or concentrated | C | Use Hastelloy B-3 or C-276 |
| Phosphoric, acetic, formic acids | A | Good to excellent when non-aerated and free of oxidising contaminants |
| Hydrofluosilicic acid | A | Standard material |
| Nitric acid, any concentration | C | Never. Rapid attack; nitric is strongly oxidising |
| Ferric chloride, cupric chloride, hypochlorite | C | Never. Oxidising salts attack Ni-Cu severely, even in trace amounts |
| Ammonia, anhydrous or oxygen-free | A | Suitable |
| Ammonia, moist and aerated | C | Stress-corrosion cracking. A classic Ni-Cu failure mode. Avoid entirely |
| Chlorine, dry | A | Suitable to ~200 °C |
| Chlorine, wet | C | Not recommended |
| Steam, condensate, feedwater | A | Excellent. Long-standing feedwater heater material |
| Sour service (H₂S) | A | Accepted by NACE MR0175 / ISO 15156-3 in the annealed or hot-worked condition at ≤ 35 HRC |
| Sulfur-bearing gases above 315 °C | C | Sulfidation and grain-boundary attack. Hard limit for hot gas service |
| Mercury | C | Liquid-metal cracking risk |
| Chloride environments generally | A | Effectively immune to chloride stress-corrosion cracking, the main reason to choose it over 304/316 |
Ratings are for screening only and assume annealed material and clean process conditions. Trace oxidising contaminants, aeration, unexpected velocity and galvanic coupling all change the outcome. Corrosion allowance and final material selection must be confirmed by a qualified corrosion engineer against your actual stream analysis.
Alloy 400 corrosion media compatibility checker
Pick the medium, concentration, temperature and aeration state, then get a screening verdict, the governing failure mode and an alternative grade if Alloy 400 is the wrong choice.
Screening tool based on published Ni-Cu corrosion tables and industry practice. It does not replace coupon testing or a corrosion engineer's review, and it cannot see contaminants you have not told it about. Jiangyin Jiangnan Metal Co., Ltd. provides it for guidance only and accepts no liability for material selection decisions.
Seawater velocity & fouling window calculator
Alloy 400 fails at both ends of the velocity range: deposits and crevices at low flow, erosion-corrosion at extreme flow. Enter your duty to find where you sit in the window.
Guidance figures reflect general industry practice for nickel-copper alloy in natural seawater. Actual limits depend on geometry, turbulence, entry effects, galvanic coupling and biofouling control. Verify against your project specification.
Service temperature safety assessment
Enter service temperature, atmosphere and duration, then get a verdict, the governing mechanism and an alternative grade where Alloy 400 runs out.
Screening guidance only. Code design must use ASME Section II Part D allowable stresses for UNS N04400, which are tabulated to 425 °C (800 °F).
NACE MR0175 / ISO 15156 sour-service compliance checker
Alloy 400 has an unusually simple sour-service rule. Enter your conditions and the delivered hardness to confirm compliance.
First-pass screening against NACE MR0175 / ISO 15156-3 for UNS N04400. Final acceptance requires review by a qualified materials engineer against the edition of the standard in force at contract date, and may require project-specific qualification testing. Provided for guidance only.
Alloy 400 vs K-500, Inconel 625, Incoloy 825, 316L and Cu-Ni
Alloy 400 is rarely the strongest or the most universally resistant candidate. It is chosen when the environment is reducing, when chloride SCC must be eliminated, or when hydrofluoric acid is present. It is chosen over more exotic alloys because it costs substantially less than the chromium-molybdenum nickel grades.
| Property | Alloy 400 | Alloy K-500 | Inconel 625 | Incoloy 825 | 316L | 70/30 Cu-Ni |
|---|---|---|---|---|---|---|
| UNS | N04400 | N05500 | N06625 | N08825 | S31603 | C71500 |
| Type | Ni-Cu solid solution | Ni-Cu age hardened | Ni-Cr-Mo-Nb | Ni-Fe-Cr-Mo-Cu | Austenitic stainless | Copper-nickel |
| Typical UTS | 550 MPa | 1,100 MPa | 830 MPa | 585 MPa | 485 MPa | 380 MPa |
| Typical YS 0.2 % | 240 MPa | 790 MPa | 415 MPa | 240 MPa | 170 MPa | 140 MPa |
| Density | 8.80 | 8.44 | 8.44 | 8.14 | 8.00 | 8.94 |
| Age hardenable | No | Yes | No | No | No | No |
| Flowing seawater | Excellent | Excellent | Excellent | Good | Pits | Good, velocity limited |
| Stagnant seawater | Crevice attack | Crevice attack | Excellent | Fair | Poor | Fair |
| Hydrofluoric acid | Best in class | Excellent | Good | Fair | Poor | Poor |
| Hot caustic | Excellent | Excellent | Excellent | Good | Fair | Poor |
| Oxidising acids (HNO₃) | Fails | Fails | Excellent | Excellent | Excellent | Fails |
| Chloride SCC | Immune | Immune | Immune | Resistant | Susceptible | Immune |
| Max service in air | ~540 °C | ~480 °C | ~980 °C | ~540 °C | ~870 °C | ~300 °C |
| Relative cost | ≈ 3 × | ≈ 5–6 × | ≈ 6–7 × | ≈ 4 × | 1 × baseline | ≈ 1.5 × |
| Choose it when | Seawater, HF, caustic, reducing acids, no chloride SCC | Same media, 3× the strength needed | Oxidising + reducing, stagnant seawater, high temperature | Sulfuric & phosphoric acid, mixed acids | General service, cost driven | Condenser tubing, low velocity seawater |
Cost multiples are indicative index values relative to 316L for hot-forged bar, FOB China, and move with LME nickel and copper. We do not publish absolute prices because they change weekly and depend on size, quantity, certification and lead time. Contact us for a current range.
Material substitution finder: should I use Alloy 400 instead?
Tell us what you are using now and what is driving the change. The tool says whether UNS N04400 is a valid substitute, what you gain and what to watch.
Comparisons use published typical properties. Substitution decisions must be made by a qualified materials engineer considering loading, environment, joining, code approval and supply chain.
Alloy 400 Failure Modes and How to Design Them Out
Alloy 400 fails in a small, well-understood set of ways. Every one of them is avoidable at the specification stage, and almost all of them come back to the same root cause: an oxidising condition, a stagnant condition, or sulfur.
Crevice & pitting in stagnant seawater
Cause: deposits, biofouling or gasket crevices create an oxygen-depleted cell. Prevention: design for continuous flow above ~1 m/s, flush during shutdowns, eliminate crevices, avoid long standby periods with seawater in the line.
Sulfur embrittlement at temperature
Cause: sulfur from fuel, lubricants, marking paint or cutting fluid diffusing into grain boundaries above ~600 °C. Prevention: low-sulfur fuel, clean furnace, degrease thoroughly before every heating operation. This is the single biggest forging risk on this grade.
Attack by oxidising upsets
Cause: ferric or cupric ions, chlorine, hypochlorite or air ingress into an otherwise reducing stream. Prevention: confirm the full stream analysis including upset cases. Even trace oxidisers change the outcome, because a Ni-Cu alloy has no passive film to protect it.
Ammonia stress-corrosion cracking
Cause: moist, aerated ammonia or ammoniacal solutions acting on residual tensile stress. Prevention: do not use Alloy 400 in this service. Where incidental exposure is possible, stress-relieve at 540–590 °C after all forming and welding.
HF vapour and caustic SCC
Cause: aerated HF vapour, or concentrated caustic above ~300 °C, acting on high residual stress. Prevention: supply annealed or stress-relieved, avoid cold-worked material in these positions, and specify stress relief after welding.
Galvanic coupling
Cause: Alloy 400 is noble. Coupled to steel, cast iron, aluminium or zinc in seawater it accelerates their corrosion; coupled to graphite or titanium it becomes the anode. Prevention: insulate dissimilar metals, control area ratios, use sacrificial anodes deliberately.
Erosion-corrosion
Cause: very high velocity combined with entrained sand or cavitation. Prevention: keep continuous velocity within the window from the seawater tool, filter solids, avoid sharp direction changes and partially open throttling valves.
Ordering an impossible heat treatment
Cause: a drawing calling for solution treatment plus ageing on N04400. Prevention: Alloy 400 is annealed only. If the strength target needs ageing, change the grade to K-500 at design stage rather than discovering it at the mill.
How Do You Forge, Anneal, Machine and Weld Alloy 400?
Forging practice
Alloy 400 forges readily but within a narrower window than steel, and the furnace atmosphere matters more than the temperature. Our practice for UNS N04400:
- Heating: charge into a furnace already at temperature; soak uniformly. Prolonged soaking wastes the window and coarsens grain.
- Start temperature: 1,150–1,180 °C. Do not exceed 1,200 °C, or incipient melting and hot shortness follow quickly.
- Heavy reduction: above 870 °C. Light finishing blows may continue down to about 650 °C to refine grain, which is how a fine, uniform structure is developed in ring-rolled sections.
- Reduction ratio: 4:1 minimum from the input billet to break down the cast structure.
- Cooling: air cool. There is no transformation to control and no sensitisation risk.
Nickel forms a low-melting nickel-sulfide eutectic at grain boundaries. Above roughly 600 °C, sulfur from fuel oil, unburnt gas, lubricants, grease, cutting fluid, layout dye or marking paint will diffuse in and embrittle the piece, producing intergranular cracking that no subsequent heat treatment can repair. Our controls: low-sulfur fuel with slightly oxidising burner settings, dedicated clean furnace practice for nickel alloys, and complete degreasing of every piece before every heating operation. If you are subcontracting heat treatment on Alloy 400, verify that your vendor knows this. It is the most frequent cause of scrapped nickel-copper forgings in the industry.
Heat treatment
Only two thermal treatments apply, and neither of them changes strength very much:
| Treatment | Temperature | Hold | Cooling | Purpose |
|---|---|---|---|---|
| Full anneal | 870–980 °C 1600–1800 °F | ~1 h per 25 mm of section, minimum 30 min | Air cool or water quench; rate not critical | Maximum ductility and corrosion resistance. Standard delivery condition |
| Stress-relief anneal | 760–870 °C 1400–1600 °F | 15–60 min | Air cool | Softening cold-worked material without full grain growth |
| Stress equalising | 540–590 °C 1000–1100 °F | 1–3 h | Air cool | Relieves residual stress from cold work, machining or welding while retaining strength. Used before caustic or HF-vapour service |
| Solution + age | Does not exist for this alloy. There is no precipitating phase. See Alloy K-500 | |||
Alloy 400 anneal & stress-relief recipe generator
Pick the objective and section size, then get a complete, printable cycle for your heat-treatment vendor, including the sulfur-control instructions.
Cycles follow general Ni-Cu practice per ASTM B564 / B164 and published producer recommendations. Hold times assume a fully soaked charge. Always validate with a thermocouple survey and hardness check on test coupons from the same heat.
Machining
Alloy 400 is gummy and work-hardens rapidly. Machinability sits at roughly 35 % of free-machining B1112 steel, better than austenitic stainless in some operations, worse in drilling. The governing rules are rigidity, sharp tooling and never letting the tool dwell in the cut: rubbing instead of cutting glazes the surface and the next pass has to cut through work-hardened material.
- Rigid setup, minimum overhang, sharp positive-rake tools with a generous nose radius.
- Heavy positive feed to stay under the hardened layer. Reduce speed rather than feed if tool life is short.
- Flood coolant. Sulfurised cutting oils are effective but must be completely removed before any heating.
- Peck-drill and clear chips; the alloy produces long stringy chips that pack and seize.
- Where machining volume dominates the cost and the part is not forged or welded, consider free-machining N04405 bar instead.
Alloy 400 machinability parameter calculator
Pick condition, operation and tool material, then get starting cutting speed, feed, depth of cut and expected tool life.
Starting values only. Final parameters depend on machine rigidity, tool holder, coolant delivery and surface-finish requirement. Alloy 400 work-hardens, so maintain positive feed contact and never dwell.
Welding
Alloy 400 is readily welded by GTAW, GMAW and SMAW and needs neither preheat nor post-weld heat treatment for mechanical reasons. The critical requirements are cleanliness and filler selection.
- Filler metal: ERNiCu-7 (AWS A5.14) for GTAW and GMAW; ENiCu-7 (AWS A5.11) covered electrodes for SMAW. Matching-composition filler without the deoxidiser additions will produce porosity.
- Preheat: none required. Keep the workpiece above the dew point to avoid condensation.
- Interpass temperature: keep below about 150 °C.
- Cleanliness: degrease and wire-brush with a clean stainless brush. Any sulfur, lead, or low-melting metal contamination causes hot cracking.
- Post-weld: not required structurally. Specify stress equalising at 540–590 °C only where the assembly will see hot concentrated caustic, aerated HF vapour or ammoniacal service.
- Dissimilar joints: ERNiCu-7 for Alloy 400 to copper alloys; ERNiCrMo-3 (Alloy 625 filler) for Alloy 400 to steel or stainless, which tolerates dilution far better.
Alloy 400 Production Capability at Jiangyin Jiangnan Metal
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forging since 2008 and exporting to more than 40 countries. UNS N04400 is produced on the same presses and ring mills as our stainless and nickel-alloy programme, under dedicated low-sulfur furnace practice.
- Max ring OD
- 2,500mm, seamless rolled
- Max disc Ø
- 1,800mm
- Max shaft length
- 8metres
- Bar range
- 25–500mm diameter
- Single-piece weight
- 8,000kg maximum
- Min order
- 1piece, prototypes accepted
Process flow for every UNS N04400 order
- Raw materialNi-Cu billet, heat number traced, chemistry verified by OES on receipt
- CleaningFull degrease before heating, a mandatory sulfur control step
- Forging1,150–1,180 °C start, ≥4:1 reduction, finishing above 870 °C
- Ring rollingRadial-axial mill for seamless rings to 2,500 mm OD
- Annealing870–980 °C, chart recorded, low-sulfur atmosphere
- Rough machiningTo drawing with agreed stock allowance
- NDE & testingUT, PT, tensile, hardness mapping, chemistry re-check
- CertificationEN 10204 3.1 or 3.2, marking, preservation, packing
Equipment used for Alloy 400
| Group | Equipment | Capability for this alloy |
|---|---|---|
| Forging | Hydraulic open-die press | Up to 8,000 kg single-piece; shafts to 8 m, discs to Ø1,800 mm |
| Forging | 1 t / 3 t / 5 t / 9 t forging hammers | Small and medium sections, near-net blanks |
| Ring rolling | Radial-axial seamless ring mills, 3 m and 6 m | Rings 200–2,500 mm OD, rectangular, contoured and T-section |
| Heat treatment | Bogie-hearth and chamber furnaces | Anneal 870–980 °C with chart recording; dedicated low-sulfur practice for nickel alloys |
| Machining | CNC lathes, boring mills, drilling machines | Rough and finish machining, tube-sheet drilling |
| NDE | Ultrasonic flaw detection | ASTM E2375 for wrought nickel alloy products |
| NDE | Penetrant and magnetic-particle lines | PT per ASTM E165 / E1417, the applicable surface method for this alloy |
| Laboratory | Optical emission spectrometer | Full elemental analysis, calibrated daily against traceable standards |
| Laboratory | Universal testing machine, impact tester | Tensile per ASTM E8, Charpy V per ASTM E23 including sub-zero |
| Laboratory | Hardness testers, metallographic microscope | HRB / HRC / HB mapping, grain size per ASTM E112 |
Most forging shops run a mixed furnace schedule where nickel alloys share equipment with sulfur-bearing steels and oil-fired heating. On Alloy 400 that produces intergranular embrittlement that only appears after machining or in service. We run dedicated low-sulfur furnace practice for nickel alloys, degrease every piece before every heating operation, and record furnace atmosphere alongside the temperature chart. When you compare quotations for UNS N04400, ask each supplier what their sulfur control procedure is. The answer separates the shops that forge nickel from the shops that forge steel and occasionally accept a nickel order.
Alloy 400 forging weight calculator
Pick a shape and dimensions for instant net weight at the UNS N04400 density of 8.80 g/cm³, plus an estimated rough forging weight for your RFQ.
Calculated at 8.80 g/cm³. The result is the finished net weight; the rough forging weight adds the selected machining allowance. Maximum single-piece capability is 8,000 kg.
Which Standards, Testing and Certification Apply to Alloy 400 Forgings?
For UNS N04400 the governing specification is normally ASTM B564 for forgings and forged flanges or ASTM B164 for bar, with the ASME SB- equivalents where the part falls under the pressure-vessel code. Note that the ultrasonic and penetrant standards differ from those used on steel forgings, a point that causes real confusion on mixed-material projects.
ASTM A388 and EN 10228-3 are ultrasonic standards written for steel forgings, and they are frequently pasted onto nickel-alloy purchase orders by mistake. For wrought nickel alloys the applicable ultrasonic practice is ASTM E2375. Surface examination uses liquid penetrant to ASTM E165 / E1417. Magnetic particle testing is meaningless on material that may not be ferromagnetic. We will accept and work to either callout, but we will raise a technical query first so the certificate says something defensible.
| Category | Standard | What it covers |
|---|---|---|
| Forgings & flanges | ASTM B564 / ASME SB-564 | Primary product specification for N04400 forgings |
| Bar & rod | ASTM B164 / ASME SB-164 | Rod, bar, wire; includes free-machining N04405 |
| Plate | ASTM B127 / ASME SB-127 | Plate, sheet, strip |
| Pipe & tube | ASTM B165, B725, B730 | Seamless and welded product |
| Fittings | ASTM B366 | Wrought fittings |
| Aerospace | AMS 4675 | Ni-Cu bars, forgings and rings, annealed |
| Military / navy | QQ-N-281 | Class A annealed, Class B stress relieved; still cited on naval drawings |
| European | DIN 17750–17754, EN 10204 | 2.4360 product forms and inspection documents |
| Flange dimensions | ASME B16.5, B16.47 | Weld neck, blind, slip-on, orifice, long weld neck |
| Sour service | NACE MR0175 / ISO 15156-3 | Annealed or hot worked, 35 HRC maximum |
| Pressure code | ASME BPVC Section II Part B & D, Section VIII | Allowable stresses for N04400 to 425 °C |
| Ultrasonic testing | ASTM E2375 | Wrought nickel alloy products. The correct UT standard for this grade |
| Penetrant testing | ASTM E165 / E1417 | Surface examination |
| Mechanical testing | ASTM E8 / E23 / E18 / E10 | Tensile, Charpy impact, Rockwell, Brinell |
| Grain size | ASTM E112 | Metallographic evaluation |
| Certification | EN 10204 3.1 standard, 3.2 on request | 3.2 witnessed by Lloyd's, DNV, BV, ABS, TÜV or client inspector |
| Quality system | ISO 9001:2015 | Certified quality management system |
Quality gates and non-conformance handling
Every UNS N04400 order passes six hold points at which production stops until QA signs off: incoming chemistry verification, furnace atmosphere and forging temperature compliance, post-forging ultrasonic examination, annealing chart approval, mechanical test acceptance, and final NDE plus dimensional inspection. Customer-witnessed hold points can be added at any of the six at no extra charge. Any out-of-specification finding raises a formal non-conformance report within 24 hours, with root-cause analysis inside five working days and a proposed disposition sent to you before any rework is carried out. No silent repairs. Shipping and test documentation is retained for ten years.
Where Is Alloy 400 Used? Applications by Industry
Seawater systems
Pump shafts and casings, seawater valve bodies and trim, propeller shafts, firewater systems, condenser and heat-exchanger tube sheets, strainer bodies, sea chests and fasteners. Chosen for flowing-seawater life and freedom from chloride SCC.
HF alkylation units
Valve bodies and bonnets, flanges, pump components, settler and stripper internals, acid relief and regeneration systems. Alloy 400 is the industry reference material for hydrofluoric acid across the full concentration range.
Caustic and reducing acid plants
Caustic evaporator components, chlor-alkali equipment, hydrochloric and sulfuric acid service under non-aerated conditions, hydrofluosilicic acid, and chlorinated solvent plants.
Sour service & offshore
Wellhead and Christmas-tree components, subsea hardware, downhole tools, valve stems and seat rings. Accepted by NACE MR0175 / ISO 15156-3 at ≤35 HRC in the annealed or hot-worked condition.
MSF and RO plants
High-pressure pump components, brine circulation hardware, evaporator internals and instrument fittings in warm high-chloride brine where stainless steel cracks.
Low-temperature service
Valve bodies, pump parts and structural components to −250 °C. Alloy 400 has no ductile-to-brittle transition and gains both strength and toughness as temperature falls.
Feedwater and steam
Feedwater heater components, condensate systems, steam service hardware and nuclear auxiliary equipment.
Pulp & paper, pharmaceutical, food
Digester and bleach-plant hardware in non-oxidising positions, process vessels, agitator shafts and pump components handling brine and alkalis.
How to Specify and Order an Alloy 400 Forging
A complete enquiry can be quoted the same day. These seven items remove most of the back-and-forth on nickel-copper forgings:
- Generic designationSpecify UNS N04400 / ASTM B564, not the Monel® trade name, so any qualified producer can legally quote
- Product form & standardB564 forgings and flanges, B164 bar, B127 plate. Add the ASME SB- prefix for code work
- DimensionsDrawing with tolerances, or rough dimensions plus the machining stock you want left on
- Delivery conditionAnnealed for corrosion service. Only ask for hot-finished or cold-drawn if you need the strength
- Testing & NDEUT per ASTM E2375, PT per ASTM E165 / E1417, hardness mapping for sour service
- CertificationEN 10204 3.1 standard, or 3.2 witnessed. Add a NACE MR0175 statement for oil and gas
- CommercialQuantity, delivery target, incoterm and destination port
Ten Mistakes Engineers Make When Ordering Alloy 400
| # | Mistake | Fix |
|---|---|---|
| 1 | Calling for solution treatment and ageing. Alloy 400 has no precipitating phase and cannot be aged. The order cannot be fulfilled as written | Specify annealed. If the strength target genuinely needs ageing, change the grade to Alloy K-500 / N05500 at design stage |
| 2 | Writing "Monel 400" on the purchase order. That is a Special Metals trademark and strictly can only be filled by them | Write "UNS N04400 / ASTM B564", the generic designation any qualified producer can supply |
| 3 | Using it in stagnant seawater. Crevice and pitting attack develops under deposits during idle periods | Design for continuous flow, flush during shutdown, or move to Inconel 625 or titanium for standby systems |
| 4 | Missing an oxidising contaminant. Trace ferric or cupric ion, chlorine or air ingress destroys an otherwise perfect selection | Provide the full stream analysis including upset and start-up cases, not just the normal composition |
| 5 | Copying steel NDE callouts. ASTM A388 and EN 10228-3 are steel ultrasonic standards; magnetic particle testing assumes ferromagnetism this alloy may not have | UT per ASTM E2375, PT per ASTM E165 / E1417 |
| 6 | Assuming it is non-magnetic. The Curie temperature sits near room temperature and moves with iron content | If low permeability matters, state the maximum value and the temperature at which it applies, and require verification on the actual heat |
| 7 | Ignoring sulfur contamination before heating. Marking paint, cutting fluid and oil-fired furnaces embrittle the alloy irreversibly | Require the supplier to state their sulfur control procedure. Degrease before every heating operation |
| 8 | Specifying cold-worked material for SCC-prone service. Residual stress plus HF vapour, hot caustic or ammonia causes cracking | Specify annealed, or stress equalise at 540–590 °C after all forming and welding |
| 9 | Substituting N04405 into a forging or weldment. The free-machining grade has raised sulfur and cracks when hot worked or welded | N04405 is for machined bar parts only. Never substitute it for N04400 in forgings |
| 10 | Galvanic coupling without an area-ratio check. Alloy 400 is noble and will accelerate attack on steel, aluminium or zinc connected to it in seawater | Insulate dissimilar metals, control the anode-to-cathode area ratio, and plan sacrificial anodes deliberately |
Instant Alloy 400 RFQ generator
Fill in what you know and get a complete, professional enquiry text ready to email, WhatsApp or paste into your procurement system.
Drawing Callout Template for Alloy 400
Copying this block into the material box of a drawing removes most ordering ambiguity on nickel-copper forgings:
| Line | Text |
|---|---|
| MATERIAL | UNS N04400 per ASTM B564 (also satisfies ASME SB-564, DIN 2.4360 / NiCu30Fe, BS NA13, JIS NW4400) |
| CONDITION | Annealed 870–980 °C. Ageing not applicable; solid-solution alloy |
| HARDNESS | ≤ 35 HRC where NACE MR0175 / ISO 15156-3 applies; report actual HRB otherwise |
| PROCESS | Forging ratio ≥ 4:1. Low-sulfur furnace atmosphere mandatory. Degrease before every heating operation |
| NDE | UT per ASTM E2375; PT per ASTM E165 Type I Method C. Do not specify MT; material may be non-ferromagnetic |
| CERTIFICATION | EN 10204 3.1 mill certificate; 3.2 third-party witnessed on request |
| MARKING | Heat number, specification and condition, low-stress stamp or vibro-etch on a non-functional surface. No sulfur-bearing marking paint |
Glossary of Alloy 400 Terms
- Alloy 400
- Generic name for the ~66 % nickel, ~31.5 % copper solid-solution alloy designated UNS N04400.
- Monel® 400
- Registered trademark of Special Metals Corporation for their material of this chemistry. Generic equivalents are UNS N04400, ASTM B564, DIN 2.4360.
- UNS N04400
- Unified Numbering System designation, the unambiguous way to specify the alloy on a purchase order.
- UNS N04405 / Alloy 405
- Free-machining variant with sulfur raised to 0.025–0.060 %. Bar only; not for forgings or weldments.
- Alloy K-500 / UNS N05500
- Age-hardenable nickel-copper alloy with aluminium and titanium additions, roughly three times the yield strength of Alloy 400.
- 2.4360 / NiCu30Fe
- European Werkstoff number and material name for the same chemistry.
- ASTM B564
- Standard specification for nickel-alloy forgings, including forged flanges. It is the primary product specification for our Alloy 400 parts.
- Solid solution
- A single-phase alloy in which the alloying elements are dissolved in the matrix. Because nickel and copper are mutually soluble in all proportions, Alloy 400 has no second phase and cannot be precipitation hardened.
- Stress equalising
- Low-temperature treatment at 540–590 °C that relieves residual stress while retaining the strength gained from cold work.
- Chloride SCC
- Chloride stress-corrosion cracking, the failure mode that limits austenitic stainless steel in warm chloride service, and to which Alloy 400 is effectively immune.
- Sulfur embrittlement
- Intergranular embrittlement caused by sulfur forming a low-melting nickel-sulfide film at grain boundaries above roughly 600 °C. Irreversible; the governing fabrication risk for this alloy.
- Erosion-corrosion
- Combined mechanical and electrochemical attack at high flow velocity or where entrained solids are present.
- NACE MR0175 / ISO 15156
- Standard governing materials for H₂S-containing oil and gas service. Accepts UNS N04400 in the annealed or hot-worked condition at 35 HRC maximum.
- EN 10204 3.1 / 3.2
- Inspection document types. 3.1 is issued by the manufacturer's independent QA; 3.2 is additionally witnessed by a third party or the purchaser.
- ERNiCu-7 / ENiCu-7
- AWS classifications for nickel-copper welding filler wire and covered electrodes used to join Alloy 400.
Frequently Asked Questions About Alloy 400 / UNS N04400
Are Alloy 400, Monel 400, UNS N04400 and 2.4360 the same material?
Yes. They all describe the same nickel-copper alloy containing roughly 63–70 % nickel and 28–34 % copper. Monel® 400 is a registered trademark of Special Metals Corporation. UNS N04400, ASTM B564, DIN 2.4360 / NiCu30Fe, BS NA13 and JIS NW4400 are the generic designations that independent producers such as Jiangyin Jiangnan Metal Co., Ltd. supply against. Specify the generic designation on your purchase order and any qualified producer can quote.
Can Alloy 400 be age hardened or heat treated to higher strength?
No. Alloy 400 is a single-phase solid-solution alloy and cannot be strengthened by precipitation hardening, because there is no phase to precipitate. Its only routes to higher strength are cold work and the stress-relief treatments that follow it. If you need a precipitation-hardened nickel-copper alloy, the correct grade is Alloy K-500 (UNS N05500), which contains about 2.7 % aluminium and 0.6 % titanium and is aged around 595 °C to roughly three times the yield strength of Alloy 400.
What is the chemical composition of Alloy 400 / UNS N04400?
Per ASTM B564 and ASTM B164: nickel plus cobalt 63.0 % minimum, copper 28.0–34.0 %, iron 2.50 % maximum, manganese 2.00 % maximum, carbon 0.30 % maximum, silicon 0.50 % maximum, sulfur 0.024 % maximum. A typical mill analysis lands near 66 % Ni and 31.5 % Cu. Full detail is in Table 2.
What are the mechanical properties of Alloy 400 forgings?
In the annealed condition ASTM B564 requires a minimum tensile strength of 480 MPa (70 ksi), a minimum 0.2 % yield strength of 170 MPa (25 ksi) and minimum elongation of 35 %. Typical annealed values are 517–620 MPa tensile, 172–345 MPa yield, 35–60 % elongation and 60–80 HRB hardness. Cold-drawn stress-relieved bar reaches 580–830 MPa tensile. See Table 3.
Why is Alloy 400 used for seawater service?
Alloy 400 resists flowing seawater and brackish water far better than copper-nickel alloys or austenitic stainless steels, typically under 0.025 mm/year, and it is effectively immune to chloride stress-corrosion cracking, the failure mode that limits 304 and 316 in warm chloride service. It also tolerates far higher flow velocity than copper alloys without erosion-corrosion. Its weakness is stagnant seawater, where crevice and pitting attack develops under fouling and deposits, so designs must maintain flow or flush during shutdowns.
Is Alloy 400 suitable for hydrofluoric acid?
Yes, it is the reference material for HF service and is used throughout hydrofluoric acid alkylation units in refineries, across the full concentration range and up to the boiling point. Two cautions: aerated HF is far more aggressive than deaerated, and stress-corrosion cracking has been reported in moist HF vapour containing oxygen. For those positions specify annealed or stress-equalised material and avoid cold-worked components.
Where should Alloy 400 not be used?
Alloy 400 has no chromium and therefore no passive film, so it fails in oxidising conditions. Avoid:
- Nitric acid and other oxidising acids: rapid attack at any concentration
- Ferric chloride, cupric chloride, hypochlorite and other oxidising salts, even in trace amounts
- Moist aerated ammonia: causes stress-corrosion cracking
- Sulfur-bearing atmospheres above about 315 °C: sulfidation attack
- Stagnant seawater: crevice and pitting corrosion under deposits
- Mercury: liquid-metal cracking
- Wet chlorine and strongly aerated mineral acids
For strongly oxidising, mixed-acid or high-temperature service use Inconel 625, Incoloy 825 or Hastelloy C-276 instead.
What is the maximum service temperature of Alloy 400?
About 480–540 °C (900–1000 °F) for continuous service in air. ASME Section VIII Division 1 lists allowable stresses for N04400 up to 425 °C (800 °F), which is the practical ceiling for code pressure parts. In sulfur-bearing atmospheres the limit drops to about 315 °C because of sulfidation. At the other end Alloy 400 has no ductile-to-brittle transition and stays tough down to cryogenic temperatures. It is a standard material for service to −250 °C.
Is Alloy 400 magnetic?
It depends on the heat and the temperature. The Curie temperature of UNS N04400 falls between roughly 20 °C and 50 °C, moving with iron and manganese content within the specification band. A low-iron heat may be essentially non-magnetic at room temperature; a high-iron heat will be weakly ferromagnetic at the same temperature and lose that behaviour when warmed slightly. Never assume the alloy is non-magnetic. If low permeability matters, state the maximum value and the temperature at which it must be met, and require verification on the actual heat.
Is Alloy 400 approved for NACE MR0175 sour service?
Yes, and with unusually simple conditions. NACE MR0175 / ISO 15156-3 accepts UNS N04400 for sour service in the annealed or hot-worked condition at a maximum hardness of 35 HRC, without the H₂S partial pressure, chloride or pH limits imposed on many other alloys. Annealed Alloy 400 is typically 60–80 HRB, comfortably below the limit. Cold-worked material requires specific qualification. We supply hardness-mapped forgings with a compliance statement on the certificate. Check your conditions with the NACE checker above.
What size Alloy 400 forgings can you produce?
Jiangyin Jiangnan Metal Co., Ltd. produces UNS N04400 seamless rolled rings to 2,500 mm outside diameter, forged discs and tube sheets to 1,800 mm diameter, shafts to 8 m length, bar from 25 mm to 500 mm diameter, and single-piece weights up to 8,000 kg. Minimum order is one piece, and we accept prototype and single-part enquiries. Use the weight calculator to check your part against the 8,000 kg limit.
How should Alloy 400 be forged and annealed?
Forge from 1,150–1,180 °C, taking heavy reduction above about 870 °C and light finishing blows down to 650 °C to refine grain. Never exceed 1,200 °C. Anneal at 870–980 °C for approximately one hour per 25 mm of section, then air cool or water quench. Cooling rate is not critical because there is no sensitisation. Stress equalising of cold-worked material is done at 540–590 °C.
Critically, fuel and furnace atmosphere must be low in sulfur, and every piece must be degreased before every heating operation. Sulfur from fuel, lubricants or marking paint produces irreversible intergranular embrittlement above roughly 600 °C. This is the most common cause of scrapped nickel-copper forgings.
What is the lead time for Alloy 400 forgings?
Standard annealed UNS N04400 forgings typically ship 8–10 weeks from order confirmation. Large forgings above 3 tonnes and orders requiring EN 10204 3.2 third-party witnessed inspection extend to 12–14 weeks. Quotations are issued within 24 hours of a complete enquiry.
What is the difference between Alloy 400 and Alloy K-500?
They share the same nickel-copper base and very similar corrosion resistance, but K-500 (UNS N05500) adds about 2.7 % aluminium and 0.6 % titanium so that it can be age hardened to roughly three times the yield strength of Alloy 400, around 790 MPa versus 240 MPa typical. K-500 costs considerably more, is harder to machine, and in the aged condition is more susceptible to hydrogen embrittlement in cathodically protected seawater service, which has caused documented failures in subsea fasteners. Choose Alloy 400 unless the strength is genuinely required.
How does Alloy 400 compare with 316L stainless steel in seawater?
Alloy 400 performs far better in flowing seawater and is not susceptible to chloride stress-corrosion cracking, which is the usual failure mode of 316L in warm chloride service. It also tolerates much higher flow velocity. 316L is roughly a third of the cost, easier to machine and weld, and it is the better choice in oxidising media such as nitric acid, where Alloy 400 fails rapidly. The decision comes down to whether the environment is reducing (choose Alloy 400) or oxidising (choose stainless or a chromium-bearing nickel alloy).
Technical References
Chemistry, mechanical, physical and corrosion data on this page are drawn from the published standards and engineering references below. Test results on our material test certificates are independent and traceable to calibrated laboratory equipment.
- ASTM B564/B564M, Standard Specification for Nickel Alloy Forgings, ASTM International, West Conshohocken, PA.
- ASTM B164, Standard Specification for Nickel-Copper Alloy Rod, Bar, and Wire, ASTM International.
- ASTM B127, Standard Specification for Nickel-Copper Alloy Plate, Sheet, and Strip, ASTM International.
- ASTM B165, Standard Specification for Nickel-Copper Alloy Seamless Pipe and Tube, ASTM International.
- ASTM B366, Standard Specification for Factory-Made Wrought Nickel and Nickel Alloy Fittings, ASTM International.
- ASME Boiler and Pressure Vessel Code, Section II Part B (Nonferrous Material Specifications) and Part D (Properties), latest edition, ASME.
- AMS 4675, Nickel-Copper Alloy Bars, Forgings, and Rings, Annealed, SAE International.
- QQ-N-281, Nickel-Copper Alloy Bar, Plate, Rod, Sheet, Strip, Wire, Forgings and Structural and Special Shaped Sections, US Federal Specification.
- NACE MR0175 / ISO 15156-3, Petroleum and natural gas industries — Materials for use in H₂S-containing environments in oil and gas production — Part 3: Cracking-resistant CRAs and other alloys, ISO.
- DIN 17750–17754, Nickel and nickel alloy semi-finished products, Deutsches Institut für Normung.
- EN 10204:2004, Metallic products — Types of inspection documents, CEN, Brussels.
- ASTM E2375, Standard Practice for Ultrasonic Testing of Wrought Products, ASTM International.
- ASTM E165/E165M and E1417/E1417M, Liquid Penetrant Testing, ASTM International.
- ASM Handbook, Volume 2: Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, ASM International, Materials Park, OH. Section on nickel-copper alloys.
- ASM Handbook, Volume 13B: Corrosion: Materials, ASM International. Corrosion of nickel and nickel alloys.
- ASM Specialty Handbook: Nickel, Cobalt, and Their Alloys, J.R. Davis (ed.), ASM International.
- Special Metals Corporation, MONEL® alloy 400 technical bulletin, publication number SMC-053.
- Nickel Institute, Corrosion Resistance of Nickel-Containing Alloys in Hydrofluoric Acid, Hydrogen Fluoride and Fluorine, publication 443.
- Nickel Institute, Corrosion Resistance of Nickel-Containing Alloys in Sodium Hydroxide, publication 281.
- ASTM E8/E8M, E23, E18, E10 and E112: tensile, impact, hardness and grain size test methods, ASTM International.
Standards cited are the revisions known at the time of the last page review. For procurement, always reference the revision in force at contract date. Trademarks and copyrights belong to their respective owners.
Request an Alloy 400 / UNS N04400 Forging Quotation
Send your drawing or dimensions with the service environment and certification level, and we will respond within 24 hours with price, lead time and confirmation of the applicable standards. Single prototypes and production quantities are both welcome. If you are not sure how to phrase the enquiry, use the RFQ generator above and paste the output into an email.
Open-Die Forging Factory
Related Nickel Alloy Forging Grades
If Alloy 400 is not the right fit for your environment, these grades cover the adjacent requirements:
- Inconel 625 (UNS N06625): when both oxidising and reducing conditions occur, or seawater is stagnant
- Incoloy 825 (UNS N08825): sulfuric and phosphoric acid, mixed acid streams
- Hastelloy C-276 (UNS N10276): the broadest chemical resistance, including wet chlorine
- Hastelloy B-3: hot concentrated hydrochloric acid
- Inconel 600 and Inconel 601: high-temperature oxidation resistance
- Incoloy 925 and Incoloy 945: high-strength sour service
- 904L and 17-4PH: stainless alternatives where cost or strength dominates
Page last reviewed 12 August 2026 by the Jiangyin Jiangnan Metal Co., Ltd. Metallurgical Engineering Team. Data is provided for engineering guidance; confirm all values against the governing specification revision for your contract.