Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Monel 400 Nickel-Copper Alloy (UNS N04400 / Werkstoff 2.4360)
Monel 400 (also written Alloy 400, Nickel 400, UNS N04400, Werkstoff 2.4360, NiCu30Fe, DIN 17743) is a solid-solution-strengthened nickel-copper alloy. Nominal composition is 63 to 70 percent nickel, 28 to 34 percent copper, with iron 2.5 max, manganese 2.0 max, carbon 0.3 max, silicon 0.5 max and sulfur 0.024 max per ASTM B164. The alloy is not precipitation hardenable; the age-hardenable variant is Monel K-500 (UNS N05500). The free-machining grade is Monel R-405 (UNS N04405) with sulfur 0.025 to 0.060 percent. Monel 400 is covered by ASTM B164 (rod, bar, wire), ASTM B127 (plate, sheet, strip), ASTM B165 (seamless pipe and tube), ASTM B163 (condenser tube), ASTM B564 (forgings and flanges), ASTM F468 (bolts), ASTM F467 (nuts), ASME SB-164, SAE AMS 4544 / 4574 / 4675 / 4730 / 4731, EN 17743, JIS NW4400, NACE MR0175 / ISO 15156-3, API RP 751 and QQ-N-281.
Monel 400 is supplied by TorqBolt as fasteners, bolts, stud bolts, nuts, washers, threaded rod, round bar, plate, sheet, tubing, seamless pipe, fittings, flanges, forgings, and wire. Mechanical properties on annealed bar: yield 25 to 35 ksi typical (F468 minimum 30 to 40 ksi depending on diameter), tensile 70 to 85 ksi, elongation 35 to 60 percent, hardness 110 to 150 HB (F468 fastener-grade capped at 25 HRC, tighter than the NACE MR0175 35 HRC ceiling for nickel-copper).
Monel 400 Characteristics and Key Properties
Monel 400 is engineered for hydrofluoric acid service above 40 percent concentration, flowing seawater up to 6 metres per second, sour gas service per NACE MR0175 / ISO 15156-3, and naval non-magnetic hardware above the Curie transition (21 to 49 degrees Celsius depending on heat). The nickel-copper couple builds a tightly adherent surface film that resists HF attack across the alkylation acid band where austenitic stainless and copper alloys fail. Under flowing seawater, corrosion stays below 0.025 mm per year. Service temperature range is approximately minus 240 to 480 degrees Celsius continuous; oxidising acids and wet chlorine attack the alloy and are excluded by service envelope. The alloy is qualified for sour-service applications per NACE MR0175 with hardness restricted to 35 HRC maximum.
Monel 400 Trade Names and International Equivalents
Monel is a registered trademark of Special Metals Corporation (Huntington Alloys, Precision Castparts Corp). The common name Monel 400 maps to identical UNS N04400 chemistry across several international designations and trade names. TorqBolt is not authorized by, affiliated with or endorsed by Special Metals.
| Designation | Standard / Body | Notes |
|---|---|---|
| UNS N04400 | Unified Numbering System (USA) | Canonical designation |
| Werkstoff 2.4360 / NiCu30Fe | DIN 17743 (Germany) | European equivalent, identical chemistry |
| EN NiCu30Fe | EN 17743 | European harmonised |
| JIS NW4400 | Japanese Industrial Standard | Japanese equivalent |
| BS 3072 to 3076 | British Standard (legacy) | UK reference, still cited on older drawings |
| AFNOR NU30 | French standard | France equivalent |
| Alloy 400 / Nickel 400 / NA13 | Trade names | Common procurement language |
| Monel R-405 (UNS N04405) | Free-machining variant | Sulfur 0.025 to 0.060 percent; NOT weldable |
| Monel K-500 (UNS N05500) | Precipitation-hardening variant | Aluminium + titanium added for age hardening |
Monel 400 Chemical Composition (UNS N04400 Element Ranges)
Monel 400 chemistry per ASTM B164, ASTM F468 Class A and DIN 17743 NiCu30Fe. Cobalt is counted as nickel per ASTM F468 NOTE B. Element-by-element ranges and the disambiguation from Monel R-405 free-machining grade are detailed on the dedicated Monel 400 chemical composition page.
| Element | ASTM B164 limit (wt%) | ASTM F468 Class A | DIN 17743 | Typical Mill Heat |
|---|---|---|---|---|
| Nickel + Cobalt | 63.0 to 70.0 | 63.0 to 70.0 | 63.0 to 70.0 | 67.0 |
| Copper | balance | balance | balance | 30.5 |
| Iron, max | 2.5 | 2.5 | 2.5 | 1.6 |
| Manganese, max | 2.0 | 2.0 | 2.0 | 1.0 |
| Carbon, max | 0.3 | 0.3 | 0.15 | 0.12 |
| Silicon, max | 0.5 | 0.5 | 0.5 | 0.25 |
| Sulfur, max | 0.024 | 0.024 (Class A); 0.025 to 0.060 (Class B / R-405) | 0.020 | 0.005 |
Monel 400 Mechanical Properties (Yield, Tensile, Hardness)
Mechanical requirements per ASTM B164 for solution-annealed bar and ASTM F468 for fastener-grade Monel 400. Strength comes from solid-solution strengthening and cold work; there is no aging step.
| Property | B164 Annealed (typical) | F468 Fastener Minimum | Cold-Drawn | Test Standard |
|---|---|---|---|---|
| Yield strength (0.2 percent offset) | 170 to 240 MPa (25 to 35 ksi) | 207 to 276 MPa (30 to 40 ksi depending on diameter) | 380 to 690 MPa | ASTM A370 |
| Tensile strength | 480 to 585 MPa (70 to 85 ksi) | 483 to 896 MPa (70 to 130 ksi) | 620 to 760 MPa | ASTM A370 |
| Elongation in 50 mm | 35 to 60 percent | 20 percent min | 15 to 30 percent | ASTM A370 |
| Hardness Brinell | 110 to 150 HB | not specified | 150 to 225 HB | ASTM E10 |
| Hardness Rockwell C (F468 cap) | not specified | 25 HRC max (tighter than NACE 35 HRC ceiling) | up to 28 HRC | ASTM E18 / NACE MR0175 |
| Density | 8.83 g/cm³ | 8.83 g/cm³ | 8.83 g/cm³ | Physical |
| Service temperature range | minus 240 to 480 degrees Celsius continuous | same | same | Oxidising air |
Monel 400 Heat Treatment (Solution Anneal Only)
Solution annealing at 816 to 871 degrees Celsius (1500 to 1600 degrees Fahrenheit) followed by air cool or water quench. There is no precipitation hardening, no aging, no temper. Stress-relief at 540 to 650 degrees Celsius is sometimes specified for thick cold-worked sections to relieve residual stress without significant strength loss. Forging temperatures range from 900 to 1175 degrees Celsius. The precipitation-hardening Monel variant is Monel K-500 (UNS N05500), age-hardened from solution-treated stock at 593 degrees Celsius for 16 hours. Full detail on the dedicated heat treatment page.
Monel 400 Welding (ERNiCu-7 / ENiCu-7)
Recommended fillers per AWS A5.14 and AWS A5.11: ERNiCu-7 wire for GTAW and GMAW, ENiCu-7 covered electrode for SMAW. Pre-weld preparation must keep the joint free of sulfur contamination. Heat input remains moderate; argon shielding is preferred for GTAW. Post-weld heat treatment is normally not required, but stress-relief at 540 to 650 degrees Celsius is sometimes specified for thick sections. Monel R-405 (UNS N04405) is NOT weldable due to its sulfur addition for free-machining. Full procedure detail on the dedicated welding page.
Monel 400 ASTM, ASME, SAE-AMS, DIN, NACE Specifications
The international specifications relevant to Monel 400 supply, qualification and inspection.
| Standard | Scope | Designation |
|---|---|---|
| ASTM B164 | Nickel-copper alloy rod, bar and wire | UNS N04400 / N04405 |
| ASTM B127 | Nickel-copper alloy plate, sheet and strip | UNS N04400 |
| ASTM B165 | Nickel-copper alloy seamless pipe and tube | UNS N04400 |
| ASTM B163 | Nickel and nickel-alloy seamless condenser and heat-exchanger tube | UNS N04400 |
| ASTM B564 | Nickel and nickel-alloy forgings | UNS N04400 |
| ASTM F468 | Nonferrous bolts, hex cap screws, socket head cap screws, studs | F 468U / F 468U4 / F 468HF (UNS N04400); F 468V (UNS N04405) |
| ASTM F467 | Nonferrous nuts for general use | UNS N04400 |
| NACE MR0175 / ISO 15156-3 | Sour-service materials qualification for H2S environments | UNS N04400 (35 HRC max) |
| DIN 17743 / Werkstoff 2.4360 | German specification for NiCu30Fe alloy | 2.4360 / NiCu30Fe |
| SAE AMS 4544 / 4574 / 4675 / 4730 / 4731 | Aerospace material specifications for Monel 400 product forms | UNS N04400 |
| QQ-N-281 | US federal specification (legacy), Class A and B | UNS N04400 / N04405 |
| API RP 751 | Recommended Practice for HF Alkylation Unit Safety, Inspection and Maintenance | Monel 400 default for bolting and reactor internals |
Monel 400 vs Monel K-500 vs Hastelloy C-276 vs Stainless Steel
Monel 400 sits in a specific corner of the alloy decision matrix. The closest cousins are Monel K-500 (precipitation-hardenable variant), Hastelloy C-276 (mixed-acid alternative), Inconel 625 (high-temperature alternative) and stainless steel 316L (cheaper alternative when seawater is benign).
| Alloy | UNS | Yield (annealed) | Best Service | vs Monel 400 |
|---|---|---|---|---|
| Monel 400 | N04400 | 170 to 240 MPa | HF, marine, sour, naval non-magnetic | Baseline |
| Monel K-500 | N05500 | 690 MPa min (aged) | Same as 400 + high bolt load | Use when load demands age-hardened strength |
| Hastelloy C-276 | N10276 | 283 MPa min | Mixed oxidising / reducing acids | Use for oxidising acids; M400 is specified for HF |
| Inconel 625 | N06625 | 414 MPa min | High temperature, oxidising | Use above 480 degrees Celsius; M400 is specified for HF and seawater |
| Stainless Steel 316L | S31603 | 170 MPa min | Benign chloride, food / pharma | Use when seawater is below 30 degrees Celsius and not flow-impingement |
Monel 400 Applications by Industry
Monel 400 dominates buyer specifications in four service environments: hydrofluoric acid (refining and HF storage), flowing seawater (marine engineering), sour gas service (oil and gas), and naval non-magnetic hardware. The alloy is over-specified for benign chloride and fresh-water service where stainless 316 will do, and under-specified above 480 degrees Celsius where Inconel 600 or 625 is required.
- HF Acid Service: gold standard above 40 percent concentration. Nickel-copper film resists hydrofluoric acid where austenitic stainless and copper alloys fail.
- HF Alkylation Units: refinery reactor internals, stripper trays, valve bodies and bolting at HF-wetted flanges per API RP 751 inspection regime.
- Marine Engineering: seawater valve trim, pump shafts, propeller shafts, ship piping bolts, stern-tube fasteners.
- Seawater Corrosion: galvanic-pair compatibility, crevice attack avoidance, biofouling guidance.
- Sour Service (NACE MR0175): UNS N04400 listed with 35 HRC hardness cap; F468 fastener-grade automatically compliant at 25 HRC.
- Naval Non-Magnetic Hardware: compass binnacles, mine countermeasure vessels, MRI hardware. Annealed condition with Lloyds Register, DNV or BV permeability acceptance test.
- Chemical Processing: dilute sulfuric acid, alkalis (sodium and potassium hydroxide), brine, neutral salts, dilute hydrochloric acid.
Monel 400 Forms and Fasteners
TorqBolt holds Monel 400 stock at the Mumbai warehouse across the form and fastener range. India domestic delivery in 3 to 7 working days; export shipments through Mumbai port (JNPT) with full mill test certificate, packing list and project-specific documentation.
| Form Category | Products |
|---|---|
| Bar and rod | Round bar (B164), wire (B164), threaded rod |
| Sheet, plate, tube, pipe | Sheet, plate (B127), tubing (B163 / B165), seamless pipe (B165) |
| Fittings, flanges, forgings | Buttweld and socket-weld fittings, flanges (B564 / ASME B16.5), forgings (B564) |
| Fasteners | Bolts (F468), hex bolts, heavy hex bolts, stud bolts, anchor bolts, socket cap screws (DIN 912), nuts (F467), hex nuts, heavy hex nuts, lock nuts, washers, screws, threaded rod |
Monel 400 Frequently Asked Questions
What is Monel 400 made of?
Monel 400 is a nickel-copper alloy with nominal composition 63 to 70 percent nickel, 28 to 34 percent copper, balance iron (2.5 max), manganese (2.0 max), carbon (0.3 max), silicon (0.5 max) and sulfur (0.024 max) per ASTM B164. UNS designation is N04400; Werkstoff is 2.4360; DIN 17743 NiCu30Fe.
Is Monel 400 the same as Monel K-500?
No. Monel 400 (UNS N04400) is solid-solution strengthened with annealed yield strength of 170 to 240 MPa. Monel K-500 (UNS N05500) adds aluminium and titanium and is age-hardened to 690 MPa minimum yield. Side-by-side detail on the Monel 400 vs K-500 page.
What is Monel 400 equivalent to?
UNS N04400 is equivalent to Alloy 400, Nickel 400, Werkstoff 2.4360, NiCu30Fe (DIN 17743), JIS NW4400, BS 3072 to 3076 and AFNOR NU30. ASTM coverage includes B164 (bar), B127 (plate), B165 (pipe), B163 (condenser tube), B564 (forgings, flanges), F467 (nuts) and F468 (bolts).
Why is Monel 400 used in hydrofluoric acid?
The nickel-copper couple builds a tightly adherent surface film that resists hydrofluoric acid attack at concentrations above 40 percent. Austenitic stainless steel and copper alloys do not match this behaviour. Monel 400 is the default bolting and reactor-internal material on HF alkylation flanges per API RP 751.
Can Monel 400 be used in sour service?
Yes, with restrictions. UNS N04400 is listed in NACE MR0175 / ISO 15156-3 with limits on hardness (35 HRC max), cold work, and partial pressure of hydrogen sulfide. F468 fastener-grade Monel 400 caps hardness at 25 HRC by design, clearing the NACE ceiling automatically.
Is Monel 400 magnetic?
Above its Curie temperature (about 21 to 49 degrees Celsius, heat-dependent) Monel 400 is paramagnetic with relative permeability close to 1.001. Cold-worked material carries higher permeability than annealed. Naval non-magnetic specifications require the annealed condition and a permeability acceptance test against Lloyds Register, DNV or BV.
Which welding filler is correct for Monel 400?
ERNiCu-7 wire per AWS A5.14 for GTAW and GMAW; ENiCu-7 covered electrode per AWS A5.11 for SMAW. Both are nickel-copper fillers matched to the N04400 chemistry. Pre-weld preparation must keep the joint free of sulfur contamination. The free-machining grade Monel R-405 (UNS N04405) is NOT weldable due to its sulfur addition.
What MTC do you supply?
EN 10204 type 3.1 by default and type 3.2 on request. Heat number, melt-shop pour date, chemistry per ASTM B164, mechanical results to ASTM F468 minima, dimensional report tied to the heat lot, hardness reading per ASTM E10 / E18, and the NACE MR0175 compliance statement when sour-service certification is requested. PMI on request, third-party witness inspection (Lloyds Register, DNV, BV, SGS) on call-out.
In which forms is Monel 400 supplied?
TorqBolt manufactures Monel 400 in fasteners, round bar, wire, sheet, plate, tubing, seamless pipe, fittings, flanges and forgings.
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