Inconel 625: Complete Properties, Specifications & Applications Guide
Everything you need to know about Inconel 625 — chemical composition, mechanical properties, ASTM specifications, temperature performance, and industry applications in one comprehensive guide.
What is Inconel 625?
Inconel 625 (UNS N06625 / W.Nr. 2.4856) is a nickel-chromium-molybdenum alloy with niobium addition that provides excellent corrosion resistance, high strength at elevated temperatures, and outstanding weldability. Developed in the 1960s for steam-line piping, it has evolved into one of the most versatile nickel alloys used across aerospace, chemical processing, marine, and nuclear industries.
Its unique combination of properties — oxidation resistance to 980°C, pitting/crevice corrosion resistance, high fatigue strength, and ease of fabrication — makes Inconel 625 the go-to material for engineers facing extreme environments.
🔑 Key Properties at a Glance
Chemical Composition
Ni: 58% min
Cr: 20-23%
Mo: 8-10%
Nb+Ta: 3.15-4.15%
Fe: 5% max
Mechanical Properties
Tensile: 827-1034 MPa
Yield: 414-655 MPa
Elongation: 30-45%
Hardness: 170-210 HB
Key Characteristics
✔ Oxidation resistant to 980°C
✔ Excellent pitting resistance
✔ Outstanding weldability
✔ Non-magnetic
🧪 Chemical Composition (ASTM B443 / AMS 5599)
| Element | Min (%) | Max (%) | Role in Alloy |
|---|---|---|---|
| Nickel (Ni) | 58.0 | — | Base element; corrosion resistance |
| Chromium (Cr) | 20.0 | 23.0 | Oxidation resistance |
| Molybdenum (Mo) | 8.0 | 10.0 | Pitting resistance; solid solution strength |
| Niobium + Tantalum (Nb+Ta) | 3.15 | 4.15 | Precipitation strengthening |
| Iron (Fe) | — | 5.0 | Cost control; solid solution strength |
| Carbon (C) | — | 0.10 | Carbide formation (controlled) |
| Manganese (Mn) | — | 0.50 | Deoxidizer |
| Silicon (Si) | — | 0.50 | Deoxidizer |
| Aluminum (Al) | — | 0.40 | Deoxidizer |
| Titanium (Ti) | — | 0.40 | Deoxidizer |
🔩 Mechanical Properties at Room Temperature
| Property | Annealed | Solution Treated | Units |
|---|---|---|---|
| Tensile Strength (Rm) | 827 min | 760 min | MPa |
| Yield Strength (Rp0.2) | 414 min | 345 min | MPa |
| Elongation (A50) | 30 min | 35 min | % |
| Hardness | 170-210 | 145-200 | HB |
| Elastic Modulus | 207 | 207 | GPa |
| Density | 8.44 | 8.44 | g/cm³ |
🌡️ Elevated Temperature Tensile Properties
| Temperature | Tensile (MPa) | Yield (MPa) | Elongation (%) |
|---|---|---|---|
| 20°C | 830-1034 | 414-655 | 30-45 |
| 200°C | 760-920 | 350-520 | 30-42 |
| 400°C | 690-850 | 310-480 | 28-40 |
| 600°C | 620-790 | 280-430 | 25-38 |
| 800°C | 380-520 | 200-310 | 30-55 |
| 900°C | 200-280 | 100-170 | 40-65 |
| 980°C | 100-140 | 50-80 | 50-70 |
📐 Physical Properties
| Property | Value | Units |
|---|---|---|
| Melting Range | 1290-1350 | °C |
| Specific Heat (20°C) | 410 | J/kg·K |
| Thermal Conductivity (20°C) | 9.8 | W/m·K |
| Thermal Expansion (20-100°C) | 12.8 | μm/m·°C |
| Electrical Resistivity | 1.29 | μΩ·m |
| Magnetic Permeability | <1.001 | Non-magnetic |
📋 ASTM / AMS / ASME Specifications
| Product Form | ASTM / ASME | AMS | Welding |
|---|---|---|---|
| Sheet & Plate | B443 / SB-443 | AMS 5599 | — |
| Bar & Rod | B446 / SB-446 | AMS 5666 | — |
| Seamless Pipe & Tube | B444 / SB-444 | AMS 5581 | — |
| Welded Pipe & Tube | B704 / B705 | — | — |
| Forgings | B564 / SB-564 | — | — |
| Fittings | B366 / SB-366 | — | — |
| Wire | — | AMS 5837 | ERNiCrMo-3 |
🏭 Industry Applications
Aerospace & Defense
Engine thrust reversers, exhaust ducting, turbine shroud rings, bellows, expansion joints, fuel line tubing
Chemical Processing
Heat exchangers, reaction vessels, acid piping, distillation columns, flue gas scrubbers
Oil & Gas
Sour gas wellhead components, subsea manifolds, umbilical tubing, downhole tools, process piping
Marine Engineering
Seawater piping, propeller sleeves, submarine components, offshore risers, desalination plants
Power Generation
Waste incineration boilers, SOFC interconnects, biomass gasification, nuclear reactor components
Special Applications
Cryogenic storage, springs in corrosive environments, bellows seals, wire ropes
❓ Frequently Asked Questions
Q1: What is the maximum service temperature for Inconel 625?
Inconel 625 withstands oxidizing environments up to 980°C (1800°F) and reducing environments up to 870°C (1600°F). Above these temperatures, scaling and loss of cross-section may occur.
Q2: Is Inconel 625 magnetic?
No. Inconel 625 is non-magnetic with permeability < 1.001. After severe cold working, slight magnetic response may develop in the surface layer — this does not affect corrosion resistance.
Q3: Can Inconel 625 be welded?
Yes, very easily. Inconel 625 has excellent weldability using TIG, MIG, plasma arc, and resistance welding. Use ERNiCrMo-3 filler. No preheating or post-weld heat treatment required — a significant advantage over many other nickel alloys.
Q4: Annealed vs Solution-Treated — what’s the difference?
Annealed (980-1090°C + rapid quench): Higher strength, fully recrystallized. Solution Treated (1090-1200°C + rapid quench): Maximum corrosion resistance, slightly lower strength.
Q5: How does 625 compare with 316L stainless steel?
Inconel 625 dramatically outperforms 316L: PREN 50+ vs 24; max temp 980°C vs 870°C. But 625 is 10-15× more expensive — use 316L for non-critical; upgrade to 625 when 316L fails.
Q6: What delivery conditions and certifications?
We deliver in annealed or solution-treated condition per your specification. Every order includes MTC (EN 10204 3.1). NACE MR0175, NORSOK, SGS/BV/TÜV available on request.
Premium Inconel 625 — Extensive Stock, Fast Delivery
Huaxiao Alloy supplies Inconel 625 in all forms — sheet, plate, bar, pipe, tube, wire, and custom fabrication. Competitive pricing. Full certifications. 24-hour quote response.
📋 Get Your Inconel 625 Quote →
