High-performance comparison of Inconel 600, 625 and 718

Inconel 600 offers the best high-temperature oxidation resistance, Inconel 625 excels in corrosion resistance and processability, while Inconel 718 is favored for its superior high-strength mechanical properties. The optimal choice depends on specific performance requirements: Inconel 600 is suitable for heat treatment applications, Inconel 625 is suitable for corrosive environments such as chemical processing, and Inconel 718 is suitable for structural components in high-stress applications such as jet engines.

What is the difference between Inconel 600 and Inconel 625?

Inconel 625 alloy has a higher chromium content than Inconel 600 alloy. Chromium content is the main factor determining the oxidation resistance of an alloy. Therefore, Inconel 625 has better oxidation resistance than Inconel 600.

Learn about Inconel 600, 625, and 718

Inconel 600 – Chemical Composition, Properties, and Processing Comparison with Stainless Steel
Composition: Approximately 72% nickel, 14–17% chromium, and trace amounts of iron, manganese, silicon, and carbon.

Properties: Excellent oxidation and corrosion resistance, withstanding temperatures up to 1093°C. Mechanical properties include:
Hardness: 160–220 HB
Tensile Strength: 515–827 MPa
Yield Strength: 180–310 MPa
Applications: Metal stampings, heat exchangers, chemical processing components, industrial ductwork.

Inconel 625 – Mechanical Properties, Processing Challenges, and Corrosion Resistance
Composition: Nickel (58%), Chromium (20–23%), Molybdenum (8–10%), Niobium (3–4%).

Properties:
Hardness: 200–300 HB
Yield Strength: 414–827 MPa
Tensile Strength: 827–1,034 MPa
Excellent fatigue resistance and corrosion resistance, especially suitable for seawater and chemically corrosive environments.
Surface Treatment: Passivation or electropolishing can improve its corrosion resistance in marine and chemical applications.
Applications: Offshore platforms, chemical plants, marine structures, aerospace components.

Inconel 718 – Precipitation-hardening superalloy for high-load applications
Composition: Nickel-based alloy, reinforced with chromium, niobium, molybdenum, and titanium.

Properties:
Hardness: 330–410 HB after aging
Yield Strength: Up to 1,270 MPa
Tensile Strength: 1,380–1,510 MPa
Density: 8.19 g/cm³
Applications: Aerospace turbine disks, high-pressure valves, fasteners for high-load, high-temperature environments.

Technical Comparison of Inconel Alloy Grades 600, 625, and 718 – Mechanical Properties and Corrosion Resistance

Property	Inconel 600	Inconel 625	Inconel 718
Hardness (HB)	160–220	200–300	330–410
Yield Strength (MPa)	180–310	414–827	1,270
Tensile Strength (MPa)	515–827	827–1,034	1,380–1,510
Density (g/cm³)	8.47	8.44	8.19
Corrosion Resistance	Good	Excellent	Excellent
Max Service Temp (°C)	1093	982	704
Machinability	Moderate	Challenging	Difficult
Price per kg	$25–30	$40–45	$55–65
Typical Applications	Heat exchangers, ducting, metal stampings	Marine, aerospace, oil & gas components	Aerospace turbine disks, high-stress fasteners, valves

Feature	Inconel 600	Inconel 625	Inconel 718
Primary Strength	High-temperature oxidation resistance	Excellent corrosion resistance	High yield and tensile strength
Max Operating Temperature	Up to 1175 °C (2150 °F)	Up to 980 °C (1800 °F)	Up to 650 °C (1200 °F)
Corrosion Resistance	Moderate	Excellent	Good, but not its primary advantage
Mechanical Strength	Good	Good	Excellent
Weldability	Good	Excellent	Good
Key Applications	Furnace components, nuclear and chemical exchangers	Aerospace, chemical processing, marine equipment, oil and gas	Gas turbine engines, jet engines, fasteners, springs, and high-stress parts