Monel 400 (NiCu30Fe)

Description

Monel 400 (UNS N04400 / EN NiCu30Fe) per ASTM B165. Two-thirds Ni, one-third Cu solid-solution alloy. Higher strength than pure Ni or Cu (Rm ~520 MPa annealed, up to 800 MPa cold worked). Outstanding resistance to: hydrofluoric acid (unique property), seawater, alkaline solutions and reducing acids. Standard for HF acid alkylation units, marine pump shafts and chemical equipment.

Key Properties — Annealed

Rm (Tensile Strength)

480 – 690

MPa

Re / Rp0.2 (Yield)

170

MPa

A₅ (Elongation)

≥ 35.0

E (Young's Modulus)

179

GPa

Density

8.80

g/cm³

Main Designations (7)

Standard Body	Designation	Country / Region	Note
ASTM B164	Monel 400 bar (standard)	USA
UNS	N04400	USA (UNS)
EN	NiCu30Fe / 2.4360	EU
ASME	SB-164 (pressure vessel use)	USA
AMS	AMS 4730 (bar)	USA (Aerospace)
Trade Name	Monel 400 (Special Metals) / Nicorros 400 (ThyssenKrupp)	Global
JUS	Ni-Cu 30 legura; JUS C.B7.010	Yugoslavia	Monelova legura 400

Standards (7)

#	Standard Body	Designation	Country / Region	Note
1	ASTM B164	Monel 400 bar (standard)	USA	—
2	UNS	N04400	USA (UNS)	—
3	EN	NiCu30Fe / 2.4360	EU	—
4	ASME	SB-164 (pressure vessel use)	USA	—
5	AMS	AMS 4730 (bar)	USA (Aerospace)	—
6	Trade Name	Monel 400 (Special Metals) / Nicorros 400 (ThyssenKrupp)	Global	—
7	JUS	Ni-Cu 30 legura; JUS C.B7.010	Yugoslavia	Monelova legura 400

All values in wt.%

Nickel

~66.5000

Copper

28.0000 – 34.0000

Iron

≤ 2.5000

Manganese

≤ 2.0000

Carbon

≤ 0.3000

Element	Symbol	Min %	Max %	Typical %
Nickel	Ni	63.0000	—	66.5000
Copper	Cu	28.0000	34.0000	31.5000
Iron	Fe	—	2.5000	1.2000
Manganese	Mn	—	2.0000	1.0000
Carbon	C	—	0.3000	0.1500

Mechanical Properties

Condition	Code	Rm min MPa	Rm max MPa	Re min MPa	Re max MPa	A₅ min %	Z %	KV J	HB min	HB max	HRC min	HRC max	E GPa
Annealed	+A	480	690	170	—	35.0	—	—	—	—	—	—	179.0
Cold Drawn H02	H02	620	827	517	—	15.0	—	—	—	—	—	—	179.0

Physical Properties

Density

8.800

g/cm³

Melting Point

1300–1350

°C

Young's Modulus

179.0

GPa

Poisson's Ratio

0.320

—

Thermal Conductivity

21.8

W/m·K

Thermal Expansion

13.90

×10⁻⁶ /K

Specific Heat

427

J/kg·K

Electrical Resistivity

0.5480

µΩ·m

Magnetic

Heat Treatment

Annealing

Temperature:760°C – 925°C

Medium:Air or inert

Duration:15-60 min

Cooling:Air or water cool

Hardness After:Rm 480-690 MPa

Annealing temperature affects grain size — lower = finer grain.

Stress Relief

Temperature:275°C – 345°C

Medium:Air oven

Duration:1-2 h

Cooling:Air cool

Hardness After:Minimal

After cold work.

Machinability

Machinability Rating

relative to AISI B1112 = 100%

35.0%

Very Difficult

Turning Speed (HSS)

m/min

Turning Speed (Carbide)

m/min

Feed Rate (Turning)

0.080

mm/rev

Drilling Speed (HSS)

m/min

Milling Speed (Carbide)

m/min

Coolant	High-pressure flood coolant mandatory
Chip Formation	Long gummy work-hardening chips; built-up edge tendency
Tool Material	TiAlN carbide K10-K20; positive rake; 30-60 m/min turning
Surface Finish	Ra 0.8-3.2 um

Difficult — similar to 316L but more work-hardening due to Ni-Cu. Constant feed essential.

Applications

Marine

Ship propeller shafts, seawater valve bodies, pump casings for seawater and brine service.

HF Acid Plant

HF acid alkylation unit piping, heat exchangers and vessel internals — primary HF application.

Chemical

Neutral and alkaline salt solutions, hydrofluoric acid, sulphuric acid and organic acids.

Food Processing

Cooking and processing vessels for acidic foods where iron contamination must be avoided.

Technical Notes

💧

HF Acid Resistance

Monel 400 is uniquely resistant to hydrofluoric acid (HF) at all concentrations and temperatures — HF dissolves most alloys. The standard material for HF alkylation units in petroleum refineries. No other common alloy can replace it for concentrated HF service.

✅

Monel 400 vs Inconel 625 in seawater

Monel 400: good seawater resistance, lower cost, lower strength. Inconel 625: better pitting resistance (PRE=52 vs ~15), better for aggressive Cl. Use Monel 400 for general seawater; 625 for severe chloride pitting environments.