Alloy 625 vs 825

Alloy 625 vs 825 – What’s the Difference

ByAbhishek Modak

When it comes to industrial projects, the material you choose can be just as important as the design. Two popular alloys are alloy 625 and alloy 825. Let’s compare these two materials so you can make an informed decision about which one is right for your project.

Difference Between Alloy 625 and 825

Alloy 625 and 825 are nickel-based superalloys developed by Special Metals Corporation. As with most superalloys, both of these materials boast excellent corrosion resistance and high-temperature strength. However, there are several differences between them that you should be aware of when making a decision about which one to use for your project.

Performance

The main difference between alloy 625 and 825 is their performance at elevated temperatures. Alloy 625 has a higher melting point than alloy 825—at 2,000°F (1,093°C) compared with 1,742°F (950°C). This means that alloy 625 will retain its strength for longer periods of time at higher temperatures than alloy 825 will. However, alloy 825 has superior stress rupture strength—the ability to resist cracking from cyclic loads—at temperatures up to 1,200 °F (649 °C).

Applications

When it comes to applications, both alloys have some similarities but also some notable differences. Both alloys can be used in chemical processing equipment such as heat exchangers, pumps and valves; they can also be used in oil refining equipment and other industrial components exposed to high temperatures and corrosive environments. However, due to its higher melting point and superior stress rupture strength at elevated temperatures, alloy 625 is often used in more demanding applications such as gas turbines and nuclear reactors, while alloy 825 is frequently used in less demanding applications such as exhaust manifolds and chemical processing equipment.

Chemical Composition

Alloy 625 is an austenitic nickel-chromium-molybdenum alloy that contains 9% Ni, 22% Cr, 3% Mo, and traces of manganese, silicon, iron, and carbon. Alloy 825 is an austenitic nickel-iron-chromium alloy that contains 38% Ni, 20% Fe, 2.5% Cr, and traces of manganese, silicon, copper, and titanium.

Tensile Strength

One of the most important properties of any material is its tensile strength, which is a measure of the material’s ability to resist being pulled apart by forces acting on it. Alloy 625 has a tensile strength of 125 ksi (862 MPa), while alloy 825 has a tensile strength of 100 ksi (690 MPa)

Yield Strength

The yield strength of a material is the stress at which it begins to deform plastically. This is an important property for materials that will be used in structures or other applications where they will be subject to loads that could cause them to yield. Alloy 625 has a yield strength of 95 ksi (655 MPa), while alloy 825 has a yield strength of 75 ksi (517 MPa).

Elongation

Elongation is a measure of a material’s ability to deform before breaking. This property is important for materials that will be subject to loads that could cause them to deform significantly before breaking. Alloy 625 has an elongation of 30%, while alloy 825 has an elongation of 20%.

Density

The density of a material is the mass per unit volume. This property is important for many applications where weight and/or space are considerations. Alloy 625 has a density of 0.305 lb/in^3 (8.44 g/cm^3), while alloy 825 has a density of 0.292 lb/in^3 (8.1 g/cm^3).

Conclusion:

When deciding which material is best for your project’s needs, it’s important to consider the differences between alloys 625 & 825 carefully. While both materials offer excellent corrosion resistance and high-temperature strength, there are key differences that could make one better suited than the other, depending on your application requirements. Careful consideration now could save you money down the line if you choose the wrong material for your project’s needs!

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