ThePipingMart Blog Metals Monel K500 vs Inconel 625 – What’s the Difference

Monel K500 vs Inconel 625 – What’s the Difference

Monel K500 vs Inconel 625

When selecting the right material for your manufacturing needs, you may come across two similar yet distinct alloys: Monel K500 and Inconel 625. Both metals possess remarkable qualities, such as corrosion resistance, superior strength, and durability. However, upon closer inspection, there are several differences between the two. In this blog post, we’ll delve into the key features of Monel K500 and Inconel 625 and help you decide which metal to use for your next project.

What is Monel K500?

Monel K500 is a nickel-copper alloy that combines the excellent corrosion resistance of Monel 400 with greater strength and hardness. It also has good weldability and can be fabricated by all standard methods. The increased strength of the alloy is a result of additions of aluminium and titanium.

What is Inconel 625?

Inconel 625 is a nickel-chromium-molybdenum alloy with an addition of niobium that acts with the molybdenum to stiffen the alloy’s matrix and thereby provide high strength without strengthening heat treatment. Inconel 625 is used for its high strength, excellent fabricability (including joining), and outstanding corrosion resistance.

Difference Between Monel K500 and Inconel 625


Monel K500 and Inconel 625 differ in their composition. The former comprises 63% nickel, 30% copper, and 3% iron, while the latter contains 58% nickel, 20-23% chromium, and 5-9% molybdenum. Monel K500 also contains small amounts of aluminium and titanium, which help improve its strength and hardness.

Strength and Toughness

Both alloys are renowned for their high-strength properties, but Monel K500 is known for its exceptional toughness. It can withstand high-stress situations, such as impact loading and sudden shock, without breaking or fracturing. Inconel 625 has higher tensile strength than Monel K500 but is less durable than the latter.

Corrosion Resistance

One of the defining properties of both Monel K500 and Inconel 625 is their remarkable corrosion resistance in harsh environments. They are both highly resistant to pitting, crevice corrosion, and stress-corrosion cracking. However, Monel K500 is more effective at resisting sea-water corrosion, making it ideal for marine applications.

Temperature Resistance

Monel K500 and Inconel 625 can withstand high temperatures without losing their strength and resistance properties. However, Inconel 625 is better suited for high-temperature environments, with a melting point of 1350℃, whereas Monel K500 can be used up to 650℃.


Monel K500 is primarily used in marine engineering, oil and gas production, and chemical processing due to its superior corrosion resistance. It also finds applications in valve components, pump shafts, and paper production equipment. Inconel 625, on the other hand, is commonly used in aircraft and aerospace industries, combustion and power generation systems, and chemical plants. It is widely used in exhaust ducts, heat exchanger tubing, turbine shrouds, and jet engine components.

Physical Properties

The physical properties of Monel K500 are a density of 8.44 g/cm3, melting point of 1350°C, and a boiling point of 3000°C. The physical properties of Inconel 625 are a density of 8.4 g/cm3, melting point of 1350°C, and boiling point of 2900°C.

Thermal Conductivity

The thermal conductivity of Monel K500 is 100 W/(m·K) at 20°C and 70 W/(m·K) at 1000°C. The thermal conductivity of Inconel 625 is 100 W/(m·K) at 20°C and 46 W/(m·K) at 1000°C.

Thermal Expansion

The thermal expansion of Monel K500 is 13 x 10-6 /K at 20-100°C and 11 x 10-6 /K at 400-600°C. The thermal expansion of Inconel 625 is 11 x 10-6 /K at 20-100°C and 9 x 10-6 /K at 400-600°C.

Modulus of Elasticity

The modulus of elasticity of Monel K500 is 193 GPa at 20°C and 186 GPa at 600°C. The modulus of elasticity of Inconel 625 is 193 GPa at 20°C and 186 GPa at 600°C.


When it comes to choosing between Monel K500 and Inconel 625, it ultimately depends on the specific requirements of your project. If you need a highly resistant material to sea-water corrosion, Monel K500 is your best bet. However, if you require a material that can withstand high-temperature environments, Inconel 625 is the better choice. Both alloys possess excellent strength, durability, and versatility, making them suitable for various industries and applications. Consult an experienced metal supplier to help you select the right material when in doubt.

Related Post