Monel 400 vs 316L Stainless: Marine & Chemical
Date: 2026年9月10日 Categories: News Views: 404
By Shanghai Hangbo Alloy Group Co., Ltd. - China Supplier | ISO 9001:2015 | Est. 2012
Contact: sales@hangboalloy.com | hangbo@nickel-alloy.com | WhatsApp (Lisa): +86 13611656360
Quick Answer: What Is the Difference Between Monel 400 and 316L?
Monel 400 (UNS N04400) is a nickel-copper alloy (~67% Ni, ~30% Cu) and 316L (UNS S31603) is a molybdenum-bearing austenitic stainless steel. The decisive difference is chloride resistance: 316L suffers pitting and chloride stress-corrosion cracking above ~60C in chlorides, while Monel 400 is essentially immune to chloride SCC and highly resistant to seawater, hydrofluoric acid, and caustic alkalis. But Monel 400 costs 6-10x more than 316L. Rule: use 316L for general chemical service; upgrade to Monel 400 for seawater at temperature, HF acid, and caustic service where 316L fails.
Composition Comparison (wt.%)
| Element | Monel 400 (N04400) | 316L (S31603) |
|---|---|---|
| Nickel | 63-70 | 10-14 |
| Copper | 28-34 | -- |
| Chromium | -- | 16-18 |
| Molybdenum | -- | 2.0-3.0 |
| Iron | 2.5 max | Balance |
| Carbon | 0.3 max | 0.03 max |
Note: Monel 400 has no chromium — its corrosion resistance comes from the nickel-copper matrix, not a passive Cr2O3 film.
Corrosion Performance Comparison
| Environment | Monel 400 | 316L | Winner |
|---|---|---|---|
| Seawater (ambient) | Excellent | Good (pitting risk) | Monel 400 |
| Seawater (hot, >60C) | Excellent | Fails (SCC) | Monel 400 |
| Chloride SCC | Immune | Susceptible | Monel 400 |
| Hydrofluoric acid (HF) | Excellent | Poor | Monel 400 |
| Caustic (NaOH) | Excellent | Good | Monel 400 |
| Dilute H2SO4 | Good | Good | Tie |
| Oxidizing acids (HNO3) | Poor | Good | 316L |
| General atmospheric | Excellent | Excellent | Tie |
Mechanical Properties (Annealed, RT)
| Property | Monel 400 | 316L |
|---|---|---|
| Tensile Strength | 480-650 MPa | 485-620 MPa |
| Yield Strength | 170-345 MPa | 170-310 MPa |
| Elongation | 35-50% | 40-55% |
| Density | 8.80 g/cm3 | 8.00 g/cm3 |
Which One for Your Application?
| Application | Best Choice | Why |
|---|---|---|
| General chemical piping | 316L | Cost-effective |
| Seawater pump components | Monel 400 | Chloride SCC immunity |
| HF alkylation unit | Monel 400 | HF resistance |
| Caustic evaporators | Monel 400 | Caustic resistance |
| Marine fasteners | Monel 400 | Seawater + galling resistance |
| Food/pharma equipment | 316L | Hygiene + cost |
Price Comparison (2026, EXW)
| Form | Monel 400 | 316L |
|---|---|---|
| Plate | \$30-45/kg | \$4-7/kg |
| Round Bar | \$30-45/kg | \$4-7/kg |
| Tube | \$38-55/kg | \$5-9/kg |
Monel 400 costs roughly 6-10x 316L — justify it only where 316L genuinely fails.
FAQ
Q1: Is Monel 400 better than 316L?
Only in specific environments: hot seawater, HF acid, caustic, and chloride SCC service. For general chemical duty, 316L is both adequate and far cheaper.
Q2: Why does 316L fail in seawater?
Chlorides break down its passive film, causing pitting and chloride stress-corrosion cracking, especially above 60C.
Q3: What are the UNS numbers?
N04400 = Monel 400; S31603 = 316L.
Q4: Is Monel 400 magnetic?
Slightly, in the annealed condition; it becomes more magnetic when cold worked.
Q5: How much more expensive is Monel 400?
Typically 6-10 times the price of 316L.
Q6: Which resists HF acid?
Monel 400 — 316L has very poor HF resistance.
Q7: What does Shanghai Hangbo supply?
Both Monel 400 and 316L in plates, bars, tubes, and fittings with EN 10204 3.1 certification. SGS/TUV/BV available.
Contact & Complete Product Range
Shanghai Hangbo Alloy Group Co., Ltd. - China Supplier
Email: sales@hangboalloy.com | WhatsApp (Lisa): +86 13611656360 | www.nickel-alloy.com
All Grades
Ni: NI200-N6 | Monel: 400-502, K-500, R-405 | Inconel: 600-740H, X-750, 725 | Incoloy: 800-27-7MO | Hastelloy: C-276-HYBRID-BC1, N | Super Austenitic: 904L-AL-6XN | Chromium-Rich: Alloy 33 | High-Strength Stainless: Nitronic 50/60, PH13-8Mo | Chlorination: Alloy 45 | Nimonic: 75-263 | Haynes: 25-HR-160 | RA: 330/333 | Precision: 1J22-4J45 | High-Strength: 18Ni250-AerMet100 | Heating: Cr20Ni80/60 | Specialty: Alloy 20-602CA
Product Forms: Bars(6-500mm) | Tubes(OD 6-610mm) | Plates(0.1-100mm) | Forgings | Welded Pipes | Fittings | Wire(0.05-10mm) | Strip(0.02-4.0mm)
SGS/BV/TUV. www.nickel-alloy.com
