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Material: Monel 400, K500
Type: Plate, Sheet, Strip and Coil
Thickness: 0.3-1200mm, customized
Width: 0-2500mm, customized
Length: 0-12m, customized
Surface: No.1 No.2D No.2B BA No.3 No.4 No.6 No.7, etc
Monel steel sheet is a flat-rolled product manufactured from Monel alloys contain primarily nickel (52-67%) and copper (28-34%) as the principal alloying elements, with the balance consisting of iron, manganese, carbon, and silicon. The Monel alloy system was developed by the International Nickel Company (Inco) in the early 20th century and has since become the standard material for applications requiring exceptional corrosion resistance in seawater, hydrofluoric acid (HF), strong alkalis, and reducing chemical environments.
Type | Plate, Sheet, Strip, Coil | |
|---|---|---|
Surface | No.1 No.2D No.2B BA No.3 No.4 No.6 No.7 | |
Size | Width: 0-2500mm / Customized | |
Manufacturing Technique | Hot / Cold Rolled | |
Packing | Steel Frame, waterproof paper, wooden palet, wooden case or as per the dient's requirements | |
Monel Grades | Monel 400, K500 | |
Element | Monel 400 (UNS N04400) | Monel K500 (UNS N05500) |
Nickel (Ni) | 63.0 min (incl Co) | 63.0 min (incl Co) |
Copper (Cu) | 28.0-34.0 | 27.0-33.0 |
Iron (Fe) | 2.5 max | 2.0 max |
Manganese (Mn) | 2.0 max | 1.5 max |
Carbon (C) | 0.3 max | 0.25 max |
Silicon (Si) | 0.5 max | 0.5 max |
Aluminium (Al) | — | 2.30-3.15 |
Titanium (Ti) | — | 0.35-0.85 |
Sulphur (S) | 0.024 max | 0.010 max |
Phosphorus (P) | — | — |
Cobalt (Co) | — | 1.0 max |
Property | Monel 400 (Annealed) | Monel 400 (Cold-Rolled) | Monel K-500 (Age-Hardened) |
Tensile strength (MPa) | 485-620 | 620-830 | 965-1,100 |
Yield strength, 0.2% offset (MPa) | 170-345 | 415-690 | 690-830 |
Elongation in 50 mm (%) | 25-50 | 5-20 | 18-25 |
Hardness (Rockwell B) | B 60-80 | B 85-98 | C 28-35 (or B 100+) |
Modulus of elasticity (GPa) | 179 | 179 | 179 |
Density (g/cm³) | 8.80 | 8.80 | 8.44 |
Melting range (°C) | 1300-1350 | 1300-1350 | 1290-1350 |
Magnetic permeability at 25°C | <1.02 (essentially non-magnetic) | <1.02 | 1.02-1.05 (slightly magnetic in age-hardened state) |
Electrical resistivity (µΩ·cm) | 51 | 51 | 60 |
Thermal conductivity (W/m·K) | 21.8 | 21.8 | 17.5 |
Coefficient of thermal expansion (µm/m·°C, 20-100°C) | 13.9 | 13.9 | 13.7 |
Charpy V-notch impact (J, at 25°C) | 80-120 | 20-40 | 40-55 |
Charpy V-notch impact (J, at -196°C) | 70-110 | — | — |
PREN (Pitting Resistance Equivalent Number) | 29-32* | 29-32* | — |
Relative cost (x 316L sheet) | 3.0-4.0x | 3.5-4.5x | 4.0-5.0x |
Monel steel sheet is categorised by the rolling process and dimensional range. The three primary product forms are:
Sheet Type | Thickness Range | Width Range | Manufacturing Process | Primary Applications | Key Advantages |
Hot-rolled (HR) — Plate | 4.76-100 mm (3/16" to 4") | 900-3,000 mm | Slab reheated to 980-1150°C; hot-rolled through reversing mill; descaled by shotblasting and pickling (HNO3 + HF); supplied as plate lengths 2,000-12,000 mm | Chemical reactor vessels, FGD scrubber ductwork, HF alkylation towers, seawater intake systems, large-diameter storage tanks, pressure vessel heads | Lowest cost per kg; thicker sections for structural integrity; rapid delivery for thick plate (hot-rolled is faster than cold-rolled) |
Cold-rolled (CR) — Sheet | 0.3-6.35 mm (0.012" to 1/4") | 600-1,500 mm | Hot-rolled strip pickled and cold-reduced through tandem/ reversing cold mill; annealed in protective atmosphere (H2 or dissociated NH3) for bright finish; temper-rolled for flatness control | Heat exchanger baffles, damper plates, expansion bellows, reactor linings (6 mm max), marine ductwork, chlor-alkali evaporator shell, condenser tube sheets | Superior surface finish (2B, BA, or bright); tighter thickness tolerances; excellent for forming and deep drawing; better flatness |
Cold-rolled — Strip / Coil | 0.1-3.0 mm (0.004" to 0.120") | 20-600 mm | Continuous cold rolling from hot-rolled coil; multiple passes with intermediate annealing; slit to specified width; supplied in coil form or as cut-length strip | Gaskets, spring elements, diaphragm seals, small fabricated parts, wire mesh for demisters, thin linings, bellows formation, stamped components | Cost-effective for high-volume fabrication; coil allows automated feed stamping and forming; width flexibility via slitting; available as slit coil or traverse wound spool |
Standard Dimensional Availability of Monel Sheet and Plate — Thickness, Width, Length, Tolerances, and Flatness
Thickness (mm) | Width (mm) | Length (mm) | Form | Typical Tolerance (Thickness) | Typical Flatness Deviation |
0.5-1.5 | 600-1,250 | 1,000-3,000 | CR Sheet | ±0.05 mm (for <1.0 mm); ±0.08 mm (1.0-1.5 mm) | <2 mm/m (ASTM A480) |
1.5-3.0 | 600-1,500 | 1,000-4,000 | CR Sheet | ±0.10 mm | <2 mm/m |
3.0-6.0 | 600-1,500 | 1,000-6,000 | CR Sheet | ±0.13 mm | <2.5 mm/m |
6.0-12.5 | 1,000-2,500 | 2,000-8,000 | HR Plate | ±0.25 mm | <3 mm/m (ASTM A480) |
12.5-25.0 | 1,000-2,500 | 2,000-10,000 | HR Plate | ±0.35 mm | <3 mm/m |
25.0-50.0 | 1,000-2,500 | 2,000-8,000 | HR Plate | ±0.50 mm | <4 mm/m |
50.0-75.0 | 1,000-2,500 | 2,000-6,000 | HR Plate | ±0.65 mm | <5 mm/m |
75.0-100.0 | 900-2,000 | 2,000-4,000 | HR Plate | ±0.80 mm | <6 mm/m |
The surface finish of Monel sheet directly affects its corrosion resistance, cleanability, and aesthetic appearance. Unlike stainless steel, Monel does not rely on a chromium oxide passive film — its corrosion protection comes from the natural nickel-copper oxide layer that forms spontaneously in air.
Surface Treatment | Standard Designation | Surface Roughness (Ra, µm) | Process Description | Application | Corrosion Resistance Impact |
As-annealed (Bright Annealed) | BA / 2R | 0.2-0.6 (smooth, bright) | Cold-rolled sheet annealed in protective H2 or dissociated NH3 atmosphere; no scale formation; bright, reflective surface | Heat exchanger baffles, thin linings, food processing equipment, pharmaceutical vessels | Excellent — oxide-free surface; maximum corrosion resistance; no pickling residues to interfere with passivation |
As-annealed (Pickled) | 2D / 3A | 0.5-1.5 (dull grey, matte) | Hot-rolled plate annealed in air; surface scale removed by shotblasting (alumina or steel grit) followed by pickling in HNO3-HF acid bath; uniform matte grey appearance | Chemical vessels, FGD equipment, HF alkylation towers, structural components | Good — pickling restores corrosion resistance by removing chromium-depleted surface scale; slightly rougher than bright annealed but acceptable for most process applications |
Mechanically Polished (No. 4) | No. 4 | 0.3-1.0 (directional grain) | Mechanical belt polishing using 180-240 grit aluminium oxide or silicon carbide belts, progressively finer grits; produces uniform directional finish | Food contact surfaces, architectural cladding, marine fittings, valve and pump components where aesthetics plus corrosion resistance are important | Good to Excellent — polishing removes minor surface defects; does not alter corrosion resistance of the bulk alloy; directional finish aids visual inspection for crevice initiation |
Shotblasted / Gritblasted | — | 3.0-6.0 (rough, matte) | Angular steel grit or alumina particles blasted onto plate surface; provides uniform matte surface with compressive residual stress layer | Chemical tank internal surfaces, HF acid storage tank interiors, flow distributor plates where wettability is important | Controversial — compressive stress from shotblasting can improve SCC resistance BUT rough surface increases pitting initiation sites; NOT recommended for seawater service |
Electropolished | EP | 0.1-0.4 (mirror-like, Cr-enriched) | Anodic electrochemical polishing in H3PO4-H2SO4 electrolyte; smooths surface peaks (anodic dissolution) and enriches nickel content in the surface oxide film | Ultra-clean chemical reactors, semi-conductor equipment, food and dairy ultrapure systems, pharmaceutical (USP Class VI) | Superior — removes surface contaminants; enriches Ni in passive film; smoothest surface = lowest bacterial adhesion; recommended for highest-purity service |
Chemical Pickling (Light) | — | 0.5-1.5 | Light pickling in HNO3-HF mixture at 50-60°C for 5-15 minutes; removes light oxide film from stored or heat-exposed sheet | Reconditioning of existing Monel surfaces; post-weld cleaning of localised heat tint | Good — restores passive layer after weld heat tint or mill annealing without hydrogen embrittlement risk |
Passivation (Monel-specific) | — | As-supplied | Immersion in HNO3 (20-30%) at 45-55°C for 20-30 minutes; differs from stainless steel passivation — forms NiO-CuO mixed oxide film rather than Cr2O3 | All Monel surfaces for chemical service — standard post-fabrication treatment | Essential — passivation thickens the protective NiO-CuO layer; removes surface iron contamination from handling; reduces initial corrosion rate by 30-50% in the first 1000 hours of service |
While several Monel grades exist within the nickel-copper family, only Monel 400 (UNS N04400) and Monel K-500 (UNS N05500) are commonly supplied as sheet and plate.
Grade | UNS No. | EN / DIN No. | JIS No. | Sheet Availability | Key Application | Standard |
Monel 400 | N04400 | 2.4360 / NiCu30Fe | NW 4400 | Widely available — sheet, plate, strip in all thicknesses from 0.3-100 mm | General-purpose nickel-copper sheet: seawater piping, HF acid storage, chlor-alkali equipment, marine hardware, feedwater heaters | ASTM B127 / ASME SB-127 / AMS 4544 / DIN 17750 / NACE MR0175 |
Monel K500 | N05500 | 2.4375 / NiCu30Al | NW 5500 | Available — sheet and plate 1.5-50 mm; less common than 400; longer lead time | High-strength Monel: pump shafts, impellers, fasteners, propeller blades, valve stems, oil-well drilling tools | ASTM B865 / ASME SB-865 / AMS 4674 / AMS 4730 / NACE MR0175 (limited) |
Monel steel sheet is manufactured to a portfolio of international standards that govern chemical composition, mechanical properties, dimensional tolerances, testing requirements, and certification. The following table summarises the standards that apply to Monel sheet and plate procurement:
Standard / Specification | Full Title | Scope (Monel Sheet) | Key Requirements |
ASTM B127-23 | Standard Specification for Nickel-Copper Alloy (UNS N04400) Plate, Sheet, and Strip | Primary material standard for Monel 400 sheet and plate — covers all thicknesses | Chemistry per Table 1 (UNS N04400); tensile: 485 MPa min, yield: 172 MPa min (or per order); elongation: 25% min (for 1.5-50 mm); hardness: B 75-85; surface finish; flatness per A480 |
ASME SB-127 | Nickel-Copper Alloy (UNS N04400) Plate, Sheet, and Strip (Section II, Part B) | ASME Boiler & Pressure Vessel Code version of ASTM B127; required for pressure vessel applications | Same as ASTM B127 plus supplementary requirements: ultrasonic examination (SA-578), radiographic (SA-435), and hydrostatic test traceability per ASME Section VIII Div. 1 |
ASTM B865-23 | Standard Specification for Precipitation-Hardening Nickel-Copper-Aluminum Alloy (UNS N05500) Plate, Sheet, and Strip | Material standard for Monel K-500 sheet and plate | Chemistry per Table 1 (UNS N05500: Al 2.3-3.15%, Ti 0.35-0.85%); tensile in age-hardened condition: 965 MPa min; yield: 690 MPa min; elongation: 18% min; hardness: C 28-35; supplied in solution-annealed condition + ageing treatment |
ASME SB-865 | Precipitation-Hardening Nickel-Copper-Aluminum Alloy (UNS N05500) Plate, Sheet, and Strip | ASME B&PV Code version of ASTM B865 | Same as ASTM B865; supplements: impact test requirements at -196°C (if order specifies cryogenic service); ultrasonic per SA-578 |
SAE AMS 4544 | Nickel-Copper Alloy, Corrosion Resistant, Sheet and Strip (Monel 400) | Aerospace-grade Monel 400 sheet and strip — tighter tolerances and testing requirements | Chemistry per N04400; tighter tensile range (485-620 MPa annealed); grain size ASTM 5 or finer; surface quality per AMS-STD-753; magnetic permeability <1.02 |
SAE AMS 4674 | Nickel-Copper Alloy, Corrosion Resistant, Sheet and Strip (Monel K-500) | Aerospace-grade Monel K-500 sheet and strip | Chemistry per N05500; tensile 965-1100 MPa age-hardened; hardness C 28-35; AMS-STD-753 surface quality; ultrasonic per AMS 2630 |
NACE MR0175 / ISO 15156-3 | Petroleum and Natural Gas Industries — Materials for Use in H2S-Containing Environments in Oil and Gas Production | Monel 400 and K-500 for sour (H2S) service in oil and gas | Monel 400 (N04400) acceptable per Table A.27 (H2S partial pressure up to 100 kPa); hardness limit: HRC 35 max for K-500; no weld overlay restrictions; PMI required per NACE MR0175 |
DIN 17743:2021 | Nickel and Nickel Alloys — Chemical Composition of Wrought Nickel-Copper Alloys | German/European standard for Monel chemistry | EN numbering: 2.4360 (Monel 400), 2.4365 (400L), 2.4375 (K-500); chemistry within ranges similar to ASTM B127 |
DIN 17750:2021 | Nickel and Nickel Alloys — Plate, Sheet, and Strip — Properties | German/European standard for Monel sheet and plate mechanical properties and dimensions | Mechanical property ranges for NiCu30Fe (2.4360): Rm 480-600 MPa annealed; Rp0.2 180-300 MPa; A50 30-45%; dimensional tolerances per DIN EN 10029 (plate) and DIN EN 10258 (strip) |
JIS NW 4400 | Nickel and Nickel Alloy Plates, Sheets and Strips — Monel 400 | Japanese Industrial Standard for Monel 400 sheet and plate | Chemistry per Table 1 (JIS NW 4400); mechanical: tensile 480 MPa min, yield 180 MPa min, elongation 25% min; surface finish per JIS H 4554; flatness tolerances per JIS G 4304 |
EN 10204 Type 3.1 / 3.2 | Metallic Products — Types of Inspection Documents | Certification standard applicable to all Monel sheet/plate orders shipped to EU, UK, and most international projects | Type 3.1: Manufacturer inspection certificate with test results and material traceability (heat number); Type 3.2: Third-party witnessed inspection and testing by an independent inspector |
Pressure Equipment Directive (PED) 2014/68/EU | European Union Directive for Pressure Equipment | Monel sheet for pressure vessels and piping systems shipped to the EU | Category II / III / IV depending on pressure and volume; requires CE marking and notified body review for Monel pressure vessels; Material must meet EN 10204 Type 3.1 as a minimum |
Monel sheet and plate are readily weldable using all common welding processes. The key difference from stainless steel welding is that Monel does not require L-grade fillers, but it does require careful selection of filler metal to match the service environment.
Welding Process | Filler Metal | Preheat | Interpass Temp. | Post-Weld Heat Treatment | Notes |
GTAW (TIG) | ERNiCu-7 (AWS A5.14): Ni 62-69%, Cu 27-34%, Ti 1.5-3.0%, Al 1.25% max | Not required (<16°C ambient: preheat to 25°C min) | ≤ 150°C (preferred < 93°C) | Not required — Monel 400 retains properties as-welded | Preferred process for all sheet < 6.35 mm; use 100% Ar shielding; back purge with Ar for full-penetration welds on sheet > 3 mm; Ti in filler deoxidises weld pool; AC GTAW for thin sheet (<1.5 mm) |
GMAW (MIG) | ERNiCu-7 (AWS A5.14) — same chemistry as TIG filler | Not required | ≤ 150°C | Not required | For sheet > 3 mm; spray transfer preferred; shielding: 75% Ar + 25% He for better wetting; short-circuit transfer for thin sheet; spatter must be removed by grinding — can cause crevice corrosion if left on surface |
SMAW (Stick) | ENiCu-7 (AWS A5.11): Ni 62-69%, Cu 27-34%, Ti 1.0-4.0%, Al 1.0% max | Not required | ≤ 150°C | Not required | For field repairs and heavy plate > 6 mm; smaller rods (2.4 or 3.2 mm) for sheet applications; slag removal is critical — residual slag can cause crevice corrosion; not recommended for sheet < 4.76 mm due to arc instability |
SAW (Submerged Arc) | ERNiCu-7 wire + matching flux (e.g., Lincolnweld 860 or Oerlikon OP 76) | Not required | ≤ 200°C | Not required; stress relief at 590°C optional for heavy wall (>50 mm) to restore hydrogen tolerance | For heavy plate > 12 mm only — limited applicability to sheet products; flux selection critical — neutral or basic flux preferred; deep penetration can be an issue for thin plate |
Resistance welding (spot / seam) | — (autogenous or filler shim) | Not required | — | Not required | For sheet 0.5-3.0 mm; high electrical resistivity (51 µΩ·cm) favours resistance welding; Monel-to-Monel spot weld strength: 2,000-3,500 N per spot (for 1.0 mm sheet); excellent for high-volume fabrication of heat exchanger baffles and sheet metal ducts |
OBW (Orbital TIG — autogenous) | — (autogenous for tube-to-tube welding); ERNiCu-7 if filler needed for tube-to-fitting | Not required | ≤ 93°C (orbital head sensitive to heat build-up) | Not required | For Monel tubing used in heat exchangers; autogenous orbital TIG produces consistent, full-penetration welds on thin-wall Monel tube (0.7-2.0 mm wall); back purge with Ar + 5% H2 for bright internal weld surface |
Q: Is Monel the same as stainless steel?
A: No. Monel is a nickel-copper alloy (typically 63% Ni, 30% Cu), while stainless steel is an iron-based alloy (typically 70-75% Fe) with minimum 10.5% chromium. Monel does NOT contain chromium as a primary alloying element — it relies on a nickel-copper oxide (NiO-CuO) passive film rather than a chromium oxide (Cr₂O₃) film. Monel is significantly more expensive than stainless steel (3-4x the cost of 316L), offers superior resistance to seawater, HF, and reducing environments, but has lower resistance to oxidising acids (HNO₃, H₂SO₄ >80% hot) than stainless steel. They are different material families with different strengths — the correct choice depends on the specific chemical environment.
Q: What is the difference between Monel 400 and Monel K-500 sheet?
A: Monel 400 (UNS N04400) is a solid-solution-strengthened alloy supplied in the annealed condition. Its tensile strength is 485-620 MPa. Monel K-500 (UNS N05500) is age-hardenable — it contains 2.3-3.15% Al and 0.35-0.85% Ti that form Ni₃(Al,Ti) gamma-prime precipitates during ageing heat treatment at 590-595°C for 16 hours. The aged K-500 tensile strength is 965-1,100 MPa (nearly double). However, K-500 has lower elongation (18% vs 25-50%) and is more susceptible to hydrogen embrittlement in sour (H₂S) service — NACE limits K-500 hardness to HRC 35 max. K-500 sheet costs 25-40% more than Monel 400 sheet.
Q: Can Monel sheet be used for food contact surfaces?
A: Yes. Monel 400 (UNS N04400) is GRAS (Generally Recognised as Safe) per FDA 21 CFR 177.2600 for food contact surfaces. It is used in food processing equipment where salt-acid conditions exceed the capability of 316L stainless steel — for example, soy sauce fermentation tanks, cheese brining vats at 18-22% NaCl, and seafood processing equipment. However, Monel is much more expensive and is rarely specified unless 316L has shown inadequate corrosion resistance in the specific food environment. For EU market compliance, a Declaration of Compliance (DoC) per EU 1935/2004/EC is required.
Q: Does Monel 400 sheet require post-weld heat treatment?
A: No. Monel 400 does not require preheat, post-weld heat treatment, or stress relief for corrosion resistance. The alloy retains its mechanical properties and corrosion resistance in the as-welded condition. However, if the Monel weldment will be exposed to H₂S-containing environments (NACE MR0175), post-weld stress relief at 590°C for 1 hour per inch of thickness (optional) may be specified to reduce weld residual stresses. Monel K-500 requires solution annealing (870-980°C) + water quench + ageing (590°C, 16h) after welding to restore the age-hardened properties — welding in the age-hardened condition causes precipitate dissolution in the HAZ.
Q: What environments attack Monel sheet?
A: Monel is attacked by: (1) strong oxidising acids — hot concentrated nitric acid (HNO₃), sulphuric acid (H₂SO₄) above 80% concentration at elevated temperatures; (2) ferric chloride (FeCl₃) and cupric chloride (CuCl₂) solutions — these oxidise the copper phase; (3) ammonia (NH₃) solutions — ammonia forms soluble copper-ammonia complexes (Cu(NH₃)₄²⁺) that cause rapid corrosion of the copper phase, known as "ammonia grooving" or stress corrosion cracking in ammoniacal environments; (4) molten metals — Monel is quickly attacked by molten zinc, aluminium, and tin; (5) mercury and mercury compounds — mercury causes liquid metal embrittlement (LME) of Monel.
Q: Can Monel 400 sheet be formed and bent?
A: Yes. Monel 400 in the annealed condition has excellent formability with elongation of 25-50%. Minimum bend radius for Monel 400 sheet: 1x thickness (for sheet < 6.35 mm) or 2x thickness (for sheet 6.35-12.5 mm) with the bend axis transverse to rolling direction. Springback is similar to stainless steel (2-5°). For severe forming, intermediate annealing at 870-980°C followed by rapid cooling may be required. Monel K-500 sheet must be formed in the solution-annealed condition (before ageing) — forming in the age-hardened condition is not recommended due to reduced elongation (18% vs 25-50%).
Q: What is the difference between Monel 400 sheet and Hastelloy C-276 sheet?
A: They are fundamentally different alloy families: Monel 400 is a nickel-copper alloy (63% Ni, 30% Cu) while Hastelloy C-276 is a nickel-molybdenum-chromium alloy (57% Ni, 15-17% Mo, 14.5-16.5% Cr). Monel 400 costs 3-4x 316L sheet; Hastelloy C-276 costs 5-8x. Monel 400 excels in: seawater, HF acid, alkalis, reducing environments. Hastelloy C-276 excels in: oxidising acids (HNO₃, hot H₂SO₄), wet chlorine, all FGD environments, pitting/crevice corrosion resistance (PREN 69-73 vs Monel 400 PREN ~29-32). They are not interchangeable — choose Monel for HF/alkali/seawater; choose C-276 for oxidising acids/FGD/wet Cl₂.
Q: What are the lead times for Monel sheet?
A: Monel 400 sheet from stock (common sizes: 1.5-6.35 mm, 48" x 120" sheets): 1-2 weeks. Monel 400 plate from stock (6-50 mm thick): 2-4 weeks. Monel K-500 sheet (special order): 8-16 weeks, as most mills do not stock K-500 sheet and must produce a special melt. Monel 400 sheet in non-standard sizes or special surface finishes: 4-8 weeks. Lead times are longer than equivalent stainless steel because Monel is a specialty alloy with fewer global mills (Special Metals, VDM, Hangzhou Fengda, and a few others).
