Inconel 625 vs Monel 400: Both Ni alloys — completely different corrosion profiles
Inconel 625 vs Monel 400
Side-by-side chemical composition and mechanical property comparison.
Overview
Inconel 625
2.4856
Nickel-chromium-molybdenum-niobium superalloy. Solid-solution strengthened (no precipitation hardening required). Outstanding corrosion resistance from cryogenic to 982°C. Used for jet engine exhaust systems, marine components, chemical processing, flare stacks, and nuclear applications.
Monel 400
2.4360
Nickel-copper alloy with excellent resistance to seawater, hydrofluoric acid, and alkaline environments. One of the few alloys resistant to HF acid at all concentrations. Used for marine engineering, chemical processing, oil refinery piping, and valve/pump components.
| Inconel 625 | Monel 400 | |
|---|---|---|
| Material Number | 2.4856 | 2.4360 |
| Category | Nickel Alloys | Nickel Alloys |
| Standard | ASTM B443 | ASTM B127 |
Chemical composition (wt%)
| Element | Inconel 625 | Monel 400 | Overlap |
|---|---|---|---|
| C | 0–0.1% | 0–0.3% | OK |
| Si | 0–0.5% | 0–0.5% | OK |
| Mn | 0–0.5% | 0–2% | OK |
| S | — | 0–0.024% | — |
Mechanical properties
| Property | Inconel 625 | Monel 400 | Unit |
|---|---|---|---|
| tensile_strength | ≥ 827 | ≥ 480 | MPa |
| yield_strength | ≥ 414 | ≥ 170 | MPa |
| elongation | ≥ 30 | ≥ 35 | % |
Compatibility Assessment
Monel 400 is Ni-Cu for reducing environments (HF acid, seawater). Inconel 625 is Ni-Cr-Mo for oxidizing + chloride environments. 625 has 2x the strength. Monel excels in HF/seawater; 625 in hot, mixed-acid environments.
Frequently Asked Questions
Is Inconel 625 the same as Monel 400?
Inconel 625 and Monel 400 have a 35% composition overlap. Both Ni alloys — completely different corrosion profiles
Can I replace Inconel 625 with Monel 400?
Generally not recommended. The compositions differ significantly (35% overlap). These materials have different alloying concepts and are intended for different applications.
What is the difference between Inconel 625 and Monel 400?
The main differences are in the following elements: Ni. Inconel 625 is a Nickel Alloys grade, while Monel 400 is a Nickel Alloys grade.
Related Comparisons
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Data provided for reference only. Always verify against the applicable specification for critical applications.
All data is for reference only. Equivalents indicate similarity, not identity. Always verify against the applicable specification for safety-critical applications. materialref.com accepts no liability for decisions based on this data.