What is the difference between Inconel 625 and Inconel 718?
Alloy 625 and Alloy 718 (commonly referred to as Inconel 625 and Inconel 718) are both nickel alloys, both are high temperature alloys, and both belong to the Inconel family of alloys. So, what is the difference between Inconel 625 and 718?
What is the difference between Inconel 625 and 718?
We will break down the differences between Inconel 625 and Inconel 718, from chemical composition to recommended uses. First, let's cover terminology.
Terminology
You may notice that we switch back and forth between Inconel 625 and Alloy 625 throughout this article. Rather than having you go and Google "Inconel 625 and Alloy 625" yourself, we wanted to explain what these names mean.
When we use the terms Inconel 625 and Alloy 625, we are referring to the same alloy. Inconel is a registered trademark of Specialty Metals Corporation. Therefore, for legal purposes, most alloy suppliers refer to it as Alloy 625, not Inconel 625.
Composition
The first major difference between Inconel 625 alloy and 718 alloy is their chemical composition. Both are nickel alloys, but each contains different amounts of various chemicals that make them different.
Alloy 625 is primarily nickel-based, while Alloy 718 is primarily nickel+cobalt (Ni+Co). The use of Ni+Co in Alloy 718 means it is harder and stronger. Alloy 625, on the other hand, has higher levels of chromium and molybdenum, which makes it more corrosion resistant. See below for a full comparison of the chemical compositions of Inconel 625 and 718.
Properties
Inconel 625 and Inconel 718 share many common properties. Like most nickel alloys, they both have the properties of high strength, easy welding, and corrosion resistance.
However, due to the different chemical compositions of the two alloys, they also exhibit different levels of these properties. While both alloys are heat resistant, Inconel 718 has a higher melting point range of 1321-1393°C. Similarly, while both have good corrosion resistance, the higher content of chromium and molybdenum in the Inconel 625 alloy makes it more corrosion resistant.
