Both Inconel 625 and Inconel 718 are high-performance nickel-based superalloys used in demanding industries. While they share many similarities, their exact chemical compositions, mechanical properties, and performance characteristics differ, making each more suitable for specific applications.
Chemical Composition Comparison
Here is a detailed breakdown of the chemical composition for each alloy:
| Element | Inconel 625 | Inconel 718 |
|---|---|---|
| Nickel (Ni) | 58-72% | 50-55% |
| Chromium (Cr) | 20-23% | 17-21% |
| Molybdenum (Mo) | 8-10% | 2.8-3.3% |
| Niobium (Nb) | 3.15-4.15% | 4.75-5.5% |
| Iron (Fe) | 5% max | 18-21% |
| Titanium (Ti) | 0.4-1% | 0.9-1.3% |
| Aluminum (Al) | - | 0.2-0.8% |
| Cobalt (Co) | - | 1% max |
Key Points:
Inconel 625 contains higher levels of nickel and molybdenum compared to Inconel 718, giving it superior corrosion resistance.
Inconel 718 has a higher amount of iron and aluminum, contributing to its high-temperature strength and creep resistance.
Mechanical Properties Comparison
Below is a comparison of the mechanical properties of Inconel 625 and Inconel 718:
| Property | Inconel 625 | Inconel 718 |
|---|---|---|
| Tensile Strength (MPa) | 760 MPa (at room temperature) | 1,270 MPa (at room temperature) |
| Yield Strength (MPa) | 310 MPa (at room temperature) | 1,030 MPa (at room temperature) |
| Elongation (%) | 35% (at room temperature) | 15-25% (at room temperature) |
| Hardness (Rockwell B) | 90-95 HRB | 35-45 HRC (heat treated) |
| Creep Strength (MPa) | 160 MPa at 650°C | 1,000 MPa at 650°C |
| Density (g/cm³) | 8.44 g/cm³ | 8.19 g/cm³ |
| Thermal Conductivity (W/m·K) | 10.4 W/m·K (at 100°C) | 11.4 W/m·K (at 100°C) |
Key Points:
Inconel 625 is more ductile with a higher elongation at room temperature, making it suitable for applications where flexibility and toughness are crucial.
Inconel 718 exhibits significantly higher tensile and yield strength, particularly at high temperatures, which is ideal for high-stress, high-temperature environments like gas turbines and aerospace applications.
Corrosion Resistance Comparison
| Property | Inconel 625 | Inconel 718 |
|---|---|---|
| Corrosion Resistance | Excellent in seawater, acidic environments, and high-temperature corrosive conditions | Good resistance to oxidation and corrosion in high-temperature and sulfur-containing environments, but not as resistant as Inconel 625 |
| Oxidation Resistance | Very high resistance in temperatures up to 1,000°C | High oxidation resistance up to 700°C |
| Sulfur Resistance | Excellent in sulfur-containing environments | Moderate resistance to sulfur environments |
Key Points:
Inconel 625 has superior resistance to aggressive corrosive environments, including seawater and acidic conditions.
Inconel 718 is still highly resistant but more focused on high-temperature environments rather than extreme corrosion resistance.
Heat Treatment and Fabrication
| Property | Inconel 625 | Inconel 718 |
|---|---|---|
| Heat Treatment | No complex heat treatment; can be welded without significant loss of properties | Requires heat treatment to optimize mechanical properties, especially creep strength |
| Weldability | Excellent weldability without significant performance degradation | Good weldability, though careful heat treatment is required after welding |
| Machinability | Moderate machinability, especially in heat-treated forms | Good machinability in annealed condition, but can be challenging in the aged state |
Inconel 625 is easier to fabricate and weld without much loss in strength or corrosion resistance, making it suitable for applications requiring complex shapes or frequent welding.
Inconel 718 requires more careful processing, particularly heat treatment, to achieve optimal mechanical properties.
Summary
Both Inconel 625 and Inconel 718 are exceptional materials, but they excel in different areas:
Inconel 625 is the best choice when corrosion resistance, especially in marine and chemical environments, is the primary concern. It is also more ductile and easier to work with.
Inconel 718 is superior in high-temperature applications where mechanical strength, creep resistance, and high tensile strength are needed. It is commonly used in aerospace and turbine components.
Choosing the right material depends on the specific operational conditions, including temperature, mechanical load, and environmental exposure.
Our product range
| Product Form | Standard Specifications & Dimensions | Common Alloys (Examples) | Typical Standards |
|---|---|---|---|
| Bar & Rod | Round Bar: Diameter: 3mm ~ 300mm Hexagon Bar: Across Flats: 5mm ~ 100mm Square Bar: Width: 5mm ~ 150mm Length: Random, Cut-to-length, or Coils (small diameters) |
Alloy 200/201 Monel 400/K-500 Inconel 600/601/625/718 Incoloy 800/800H/825 Hastelloy C-276/C-22/B-2/B-3 |
ASTM B160, B164, B166 EN/DIN 2.4066, 2.4816, 2.4851 ASME SB-166, SB-167 |
| Wire | Diameter: 0.1mm ~ 12mm Form: Coils, spools, or straight lengths Finish: Bright, pickled, annealed |
Alloy 200/201 Inconel 600/625/X-750 Incoloy 825 |
ASTM B166, B167 EN/DIN 17752 |
| Sheet & Plate | Thickness (Sheet): 0.1mm ~ 5.0mm Thickness (Plate): 5.0mm ~ 100mm+ Width: Up to 2000mm (depending on alloy/thickness) Length: Up to 6000mm or as required |
Alloy 200/201 Monel 400 Inconel 600/625/718 Incoloy 800H/825 Hastelloy C-276 |
ASTM B162, B168, B409 EN/DIN 17742, 17744 |
| Strip & Foil | Thickness (Strip): 0.05mm ~ 2.0mm Thickness (Foil): 0.02mm ~ 0.05mm Width: Up to 600mm Condition: Cold rolled, annealed, tempered |
Alloy 200/201 Inconel 600/625 Incoloy 825 |
ASTM B162, B168 |
| Pipe & Tube | Seamless Pipe (ASTM B161/B167): - OD: 3/16" ~ 14" (6mm ~ 355mm) - Schedule: SCH 5S to XXS Welded Tube (ASTM B163/B516): - OD: 6mm ~ 300mm - Wall Thickness: 0.5mm ~ 10mm |
Alloy 200/201 Monel 400 Inconel 600/625 Incoloy 800H/825 Hastelloy C-276 |
ASTM B161, B163, B167, B516 ASME SB-163, SB-167 |
Get the complete product catalog
Our factory and testing
Our core factory and collaborative production system are equipped with modern precision cutting, processing, and heat treatment equipment, focusing on transforming raw materials into semi-finished and finished products that meet stringent standards. To ensure that every batch of materials meets or exceeds specifications, we have established a comprehensive end-to-end quality inspection system. From material properties analysis (PMI) upon raw material warehousing to dimensional accuracy control during production, and finally to mechanical property testing (such as tensile strength and hardness) and non-destructive testing before final shipment, every step is rigorously controlled by our professional quality inspection team. We promise to provide an authoritative, online-verifiable original manufacturer's material certificate (MTC 3.1) for every order, and can arrange for third-party certification bodies (such as SGS, BV, and TUV) to conduct on-site inspections and issue certificates upon customer request.
