Inconel 625 vs 718- What’s the Difference

Inconel 625 vs 718

You’re familiar with Inconel alloys if you’re in the aerospace, chemical processing, oil and gas, and marine industries. These alloys exhibit excellent corrosion resistance, mechanical properties, and high-temperature strength. Of the many Inconel alloys available, Inconel 625 and 718 are among the most popular. However, many people need help differentiating between the two and often get confused. This blog post will compare Inconel 625 vs 718 and highlight their unique features, applications, and properties.

Difference Between Inconel 625 and 718

Composition:

The primary difference between Inconel 625 and 718 is their chemical composition. Inconel 625 contains Nickel (58%), Chromium (21.5%), Molybdenum (9%), and Columbium (3.7%). On the other hand, Inconel 718 contains Nickel (52.5%), Chromium (19%), Molybdenum (5.1%), Tantalum (4.8%), Niobium (5.5%), Titanium (0.9%), and Aluminum (0.5%). Due to the different chemical compositions, the two alloys perform differently in various applications.

Weldability and Formability:

Inconel 625 exhibits excellent weldability and formability, making it ideal for various applications that require welding operations, such as chemical processing, offshore oil and gas drilling, and aerospace engineering. However, Inconel 718 has limited weldability due to its susceptibility to precipitation hardening after heat treatment. The alloy forms a hard, brittle layer after welding, which can reduce its strength and ductility.

High-Temperature Applications

Inconel 625 and 718 are popular for high-temperature applications due to their excellent thermal stability and creep resistance. However, Inconel 718 has a higher operating temperature range than Inconel 625. Inconel 718 can withstand temperatures up to 704°C (1300°F), while Inconel 625 can only withstand temperatures up to 565°C (1050°F).

Corrosion Resistance:

Both Inconel alloys exhibit excellent corrosion resistance to various hostile environments, including seawater, sulfuric acid, and hydrochloric acid. However, Inconel 625 outperforms Inconel 718 in acidic environments due to its higher nickel and molybdenum content. Inconel 625 is also resistant to pitting, crevice corrosion, and intergranular cracking, making it ideal for marine and chemical processing applications.

Applications:

Inconel 625 and 718 find extensive applications in several industries. Inconel 718 is mainly used in the aerospace industry for turbine engines, rocket motors, and aircraft exhaust systems. It is also used in nuclear reactors, gas turbines, and oil and gas drilling equipment. On the other hand, Inconel 625 finds application in chemical processing plants, marine engineering, nuclear power systems, and offshore oil and gas drilling.

Conclusion:

In conclusion, Inconel 625 and 718 are excellent materials for high-temperature and corrosive applications. While they have a few similarities, the alloys have different chemical compositions, properties, and applications. Inconel 625 is more weldable, highly corrosion-resistant, and ideal for marine and chemical processing applications. In contrast, Inconel 718 has a higher operating temperature range excellent mechanical properties, and is used mainly in the aerospace industry. When selecting which alloy to use, you must consider your specific application requirements to choose the best Inconel alloy.

senorita

senorita

Recent Posts

Categories