Inconel 625 (2.4856)

Q: What are the Mechanical Properties of Inconel 625?

Inconel 625 is designed for high stress, frequent temperature cycling and corrosive exposure. Typical values: tensile strength approx 827 MPa; yield strength (0.2 percent proof) approx 414 MPa; elongation 30-40 percent; hardness approx 220 HB (Brinell); modulus of elasticity approx 207 GPa. Suitable for exhaust manifolds, pressure vessels and structural aerospace elements.

Q: What are the Physical Properties of Inconel 625?

Typical values: density 8.44 g/cm3; melting range 1290-1350 C; thermal conductivity 9.8 W/m K; thermal expansion (20-100 C) approx 13.0 x 10^-6 per C; electrical resistivity approx 1.31 micro-ohm m. These support longevity in heat, corrosive liquids and mechanical cycling.

Q: Are there Variants or Equivalent Grades of Inconel 625?

Common options include: Inconel 625 LCF (improved low cycle fatigue resistance); Inconel 625 Plus (enhanced weldability and formability); Inconel 686 (higher Mo for superior corrosion resistance); Inconel 718 (precipitation hardened for higher tensile strength). Selection depends on fatigue performance, weldability and required mechanical properties.

Q: What is the Chemical Composition of Inconel 625?

Typical composition in percent: Nickel balance; Chromium 20.0-23.0; Molybdenum 8.0-10.0; Niobium + Tantalum 3.15-4.15; Iron 5.0 max; Carbon 0.10 max; Manganese 0.50 max; Silicon 0.50 max; Phosphorus 0.015 max; Sulfur 0.015 max; Aluminium 0.40 max; Titanium 0.40 max. This balance provides resistance in both oxidising and reducing environments while maintaining strength.

Q: Where is Inconel 625 Used?

Common applications: aerospace engine exhaust and turbine components; heat exchangers, scrubbers and ducting; marine exhaust and seawater systems; chemical processing reactors, vessels, pumps and valves; oil and gas risers, separators and flexible pipe; nuclear and power generation heat transfer and pressurised systems. Chosen for strength, corrosion protection and fabrication flexibility in extreme duty environments.

Engineered for resilient strength and corrosion resistance, Inconel 625 thrives in extreme mechanical, thermal, and chemical environments.

Inconel 625

Inconel 625 is a high-performance nickel-chromium-molybdenum-niobium alloy designed to maintain mechanical strength and corrosion resistance under the most extreme service conditions. Designated as UNS N06625 and 2.4856, this material is trusted across industries where aggressive media, elevated temperatures, and high mechanical loads are the norm.

The alloy’s balanced composition enables superior resistance to pitting, crevice corrosion, and chloride-induced stress corrosion cracking, while its high tensile and fatigue strength ensure durability in vibration-prone and pressure-intensive systems. Inconel 625 remains stable in oxidising and reducing environments alike, whether it’s aerospace turbines, offshore oil systems, or heat exchange systems in chemical plants, Alloy 625 provides long-term reliability where other materials often fail.

AVAILABLE FORMS

Intamet offers 625 in a wide range of forms, including the below:

Tubes & Pipes

Fitting & Flanges

Round Bars

Sheet & Plate

FAQs: Inconel 625

What are the Mechanical Properties of Inconel 625?

Inconel 625 is engineered to perform under high stress, frequent temperature cycling, and corrosive exposure. Its strength and flexibility allow it to withstand both static and dynamic loads in mission-critical environments.

Typical Mechanical Properties:

Tensile Strength: ~827 MPa - Delivers high load-bearing capability under elevated temperatures and corrosive conditions.

Yield Strength (0.2% proof): ~414 MPa - Maintains structural performance under mechanical strain, especially in pressure-rated components.

Elongation at Break: 30–40% - Offers excellent ductility, aiding in forming and welding without risk of fracture.

Hardness (Brinell): ~220 HB - Provides solid wear resistance while remaining machinable for precise fabrication.

Modulus of Elasticity: ~207 GPa - Ensures dimensional stability under vibration, torque, and shifting thermal gradients.

These properties make 625 ideal for exhaust manifolds, pressure vessels, and structural aerospace elements.

What are the Physical Properties of Inconel 625?

The thermal and physical characteristics of Alloy 625 support its longevity in environments involving intense heat, corrosive liquids, and mechanical cycling.

Density: 8.44 g/cm³ - Moderate weight profile that supports strength without excessive bulk.

Melting Range: 1290–1350 °C - Withstands extreme operating temperatures in jet engines, scrubbers, and incineration systems.

Thermal Conductivity: 9.8 W/m·K - Promotes controlled heat flow in thermal management systems.

Thermal Expansion Coefficient (20–100 °C): ~13.0 µm/m·°C - Supports dimensional stability through heating and cooling cycles.

Electrical Resistivity: ~1.31 µΩ·m - Provides excellent electrical isolation in components subjected to both heat and flow.

These traits enable safe, efficient operation in heat exchangers, waste gas systems, and marine propulsion assemblies.

Are there Variants or Equivalent Grades of Inconel 625?

Although Inconel 625 is a widely standardised alloy, a number of related grades and alternatives have been developed to meet specific performance demands in more specialised or extreme environments.

Common variants and alternatives include:

Inconel 625LCF: Modified for improved low-cycle fatigue resistance in cyclic thermal environments.
Inconel 625 Plus: Enhanced version for better weldability and formability, often used in automotive and structural components.
Inconel 686 (UNS N06686): A closely related high-performance alloy with higher molybdenum content for superior corrosion resistance.
Inconel 718 (UNS N07718): Precipitation-hardened alternative with higher tensile strength for aerospace and high-pressure uses.

These variants are selected based on the specific application demands for fatigue performance, weldability, or elevated mechanical properties.

What is the Chemical Composition of Inconel 625?

The alloying balance of Inconel 625 is what gives it its versatility, offering resistance to both oxidising and reducing environments while maintaining structural integrity.

Typical Composition (%):

Nickel (Ni): Balance
Base element providing corrosion resistance and structural flexibility.

Chromium (Cr): 20.0–23.0
Forms a protective oxide layer against oxidation and scaling.

Molybdenum (Mo): 8.0–10.0
Increases resistance to pitting and crevice corrosion, especially in chloride-rich systems.

Niobium + Tantalum (Nb + Ta): 3.15–4.15
Strengthens the alloy through solid-solution and precipitation hardening mechanisms.

Iron (Fe): ≤ 5.0
Acts as a balance element, improving toughness and fabrication response.

Carbon (C): ≤ 0.10
Low carbon minimises carbide precipitation during welding.

Manganese (Mn), Silicon (Si): ≤ 0.50 each
Aid in alloy stability and oxidation resistance.

Phosphorus (P), Sulfur (S): ≤ 0.015
Maintained at low levels to preserve ductility and weldability.

Aluminium (Al), Titanium (Ti): ≤ 0.40 each
Small amounts improve grain structure control and oxidation stability.

This composition is what makes Alloy 625 so reliable across chemically aggressive and structurally demanding environments.

Where is Inconel 625 Used?

Inconel 625 is specified across sectors where safety, structural integrity, and long-term performance under corrosion or high heat are non-negotiable. It performs reliably in both oxidising and reducing conditions, especially where mechanical fatigue or thermal shock are frequent.

Aerospace Engine Exhaust & Turbine Components: Withstands high thermal loads and fatigue stresses in jet engines, afterburners, and nozzle assemblies.

Heat Exchangers, Scrubbers & Ducting: Delivers long service life in pollution control systems where corrosive condensates and pressure cycling are routine.

Marine Exhaust & Seawater Systems: Resists salt spray, biofouling, and high-velocity gas in marine exhausts, piping, and condenser applications.

Chemical Processing Equipment: Used in reactors, containment vessels, pumps, and valves exposed to aggressive acids, solvents, and thermal gradients.

Oil & Gas Production Systems: Provides durability in offshore risers, separators, and flexible pipe systems exposed to sour gas and high-pressure brine.

Nuclear & Power Generation Infrastructure: Maintains mechanical performance in pressurised systems and heat transfer equipment operating under cyclic loading.

This combination of strength, corrosion protection, and fabrication flexibility makes Inconel 625 a preferred choice for extreme-duty engineering systems with zero tolerance for failure.

Need assistance or more information?
Get in touch with us today!

Have questions or need more details about this product?

Our team is here to provide expert guidance and ensure you have all the information you need to make the right choice for your project, contact us today with an enquiry!

Inconel 625 (2.4856)