Inconel 625 vs Inconel 718 - Full Comparison of Strength, Corrosion & Cost
Date: 2026年8月31日 Categories: News Views: 268
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 Inconel 625 and Inconel 718?
Inconel 625 (UNS N06625) and Inconel 718 (UNS N07718) are the two most popular nickel superalloys, but they are engineered for different jobs. 625 is a solid-solution alloy — its molybdenum + niobium give outstanding corrosion resistance in seawater, acids, and chloride environments, with moderate strength (tensile ~830-960 MPa) that needs no heat treatment after welding. 718 is a precipitation-hardened alloy — its gamma-double-prime (γ″) strengthening delivers much higher strength (tensile ~1240-1450 MPa) up to 650C, making it the default for aerospace and high-pressure components. Rule of thumb: corrosion service → 625; strength-critical service → 718.
Composition Comparison (wt.%)
| Element | Inconel 625 (N06625) | Inconel 718 (N07718) |
|---|---|---|
| Nickel | Balance (~61%) | Balance (~53%) |
| Chromium | 20-23 | 17-21 |
| Molybdenum | 8-10 | 2.8-3.3 |
| Niobium (+Ta) | 3.15-4.15 | 4.75-5.50 |
| Iron | 5 max | Balance (~18%) |
| Titanium | 0.4 max | 0.65-1.15 |
| Aluminum | 0.4 max | 0.2-0.8 |
| Cobalt | 1 max | 1 max |
Key difference: 625 carries 9% Mo for pitting resistance; 718 carries more Nb + Ti + Al for γ″ precipitation hardening.
Mechanical Properties Comparison
| Property (RT) | Inconel 625 (Annealed) | Inconel 718 (Aged) |
|---|---|---|
| Tensile Strength | 830-960 MPa | 1240-1450 MPa |
| Yield Strength | 410-550 MPa | 1030-1200 MPa |
| Elongation | 42-50% | 12-18% |
| Hardness | 175-240 HB | 331-401 HB |
| Service Limit | ~980C (oxidation) | ~650C (strength) |
Corrosion Performance Comparison
| Environment | Inconel 625 | Inconel 718 |
|---|---|---|
| Seawater / chlorides | Excellent | Good |
| Pitting / crevice | Excellent | Moderate |
| Hot acids (H2SO4, HCl) | Excellent | Moderate |
| Stress corrosion | Excellent | Good |
| H2S service (NACE) | Excellent | Good (aged) |
Which One for Your Application?
| Application | Best Choice | Why |
|---|---|---|
| Offshore piping & cladding | 625 | Corrosion + weldability |
| Chemical reactor internals | 625 | Acid resistance |
| Aircraft engine discs | 718 | Strength to 650C |
| Fasteners / bolts | 718 | High yield strength |
| Cryogenic components | 625 | Toughness |
| Turbine blades (650C+) | 718 | Creep strength |
Price Comparison (2026, EXW)
| Form | Inconel 625 | Inconel 718 |
|---|---|---|
| Round Bar | \$48-75/kg | \$38-60/kg |
| Sheet/Plate | \$50-78/kg | \$40-62/kg |
| Tube | \$60-95/kg | \$48-75/kg |
718 is typically 15-25% cheaper due to lower Mo and higher Fe content.
FAQ
Q1: Which is stronger, Inconel 625 or 718?
718 is significantly stronger (1240-1450 MPa vs 830-960 MPa) after aging.
Q2: Which has better corrosion resistance, 625 or 718?
625, due to 9% molybdenum — the best choice for seawater and acid service.
Q3: Can Inconel 718 be used at 800C?
No. Its strength drops sharply above 650C. For 800C+ strength, consider 625 (moderate) or Waspaloy/Nimonic 105.
Q4: Is Inconel 625 cheaper than 718?
No, 625 is usually 15-25% more expensive due to higher Mo and lower Fe.
Q5: Which welds better?
Both weld well, but 625 is preferred for welding because it needs no post-weld aging and resists HAZ cracking.
Q6: What are the UNS numbers?
N06625 = Inconel 625; N07718 = Inconel 718.
Q7: Which is better for marine fasteners?
For seawater strength + corrosion, 625 bolts are the standard; 718 is used where higher strength is mandatory.
Q8: What does Shanghai Hangbo supply?
Both grades in bars, plates, sheets, tubes, and forgings 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)
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