Both Inconel 718 alloy and Inconel X-750 alloy are precipitation strengthened superalloys. They all have very good high temperature strength and corrosion resistance. The properties make them fundamentally different from solid solution alloys. On the Internet, you can see many popular science articles describing this difference.

However, when comparing the Inconel 718 with the Inconel X-750, we were able to find very little reference. In this article, we will make a detailed comparison of these two alloys in terms of alloy history, chemical composition and performance.

Inconel X-750 is a relatively early superalloy. It adds four elements of aluminum, titanium, niobium and tantalum to the solid solution strengthened alloy. This structure is called a precipitation strengthened alloy. This type of alloy can obtain much higher strength than ordinary alloys through special heat treatment (aging treatment). It is designed to meet the comprehensive requirements of materials in aero-engines that need to resist high temperature, high pressure and high corrosion.

Later, with the follow-up research on alloy composition and microstructure. Inconel 718 was developed. It controls trace elements more strictly on the basis of Inconel X-750. At the same time, it adds more niobium, tantalum, and molybdenum to simultaneously improve the solid solution strengthening and precipitation strengthening effects of the alloy.

In general, the Inconel X-750 is the ancestor of the Inconel 718. And Inconel 718 can be regarded as an improved version of Inconel X-750.

Except for sulfur, Inconel 718 has stricter control of harmful elements than Inconel X-750.

Precipitation strengthened superalloys need to be placed at high temperatures for more than ten hours during aging treatment. During this time period, harmful elements can lead to the precipitation of harmful phases in the alloy. These detrimental phases significantly reduce the durability of the alloy.

Inconel 718's stricter control of silicon, manganese, and phosphorus determines that its durability at high temperatures is much better than that of Inconel X-750.

Compared to Inconel X-750, Inconel 718 has more chromium. This makes Inconel 718 better than Inconel X-750 in oxidation resistance. In addition, Alloy 718 contains molybdenum which is not present in alloy X-750. The addition of molybdenum improves the reduction corrosion resistance of Inconel 718.

Therefore, Inconel 718 is superior to Inconel X-750 in all aspects of corrosion resistance.

First, molybdenum is added to Inconel 718. This element is an ideal solid solution strengthening element. It increases the base strength of the alloy.

In addition, Inconel 718 reduces the content of aluminum and titanium on the basis of Inconel X-750, while significantly increasing the content of niobium and tantalum. This compositional design simultaneously increases the amount of both precipitation strengthening phases.

Therefore, Inconel 718 is also significantly ahead of Inconel X-750 in terms of mechanical properties.

It should be noted that although the high temperature strength of Inconel 718 is better than that of Inconel X-750. But its melting point is lower than alloy X-750. Therefore, in some higher temperature applications, Inconel X-750 also has the opportunity to perform better than Inconel 718.

It can be seen that the application fields of the two alloys have a great overlap. They are both heavily used in aerospace engine applications. However, Inconel 718 has better corrosion resistance, so it is also suitable for applications such as marine projects.

Although the Inconel 718 is ahead of the Inconel X-750 in most respects, the price difference between them is not that great. On the one hand, this is because Inconel 718 has a lower nickel content and a higher iron content. This saves the raw material cost of the alloy. On the other hand, due to the wide application of Inconel 718, its supply is large, which also reduces its marginal cost.

Therefore, if your project is hesitant about the choice of these two materials, we recommend Inconel 718 for you first. It has better performance and the same price.

Due to the addition of more chromium, molybdenum, niobium and tantalum elements, Inconel 718 is ahead of Inconel X-750 in terms of corrosion resistance and high temperature strength. At the same time, Inconel 718's control of trace elements also makes it have better long-lasting performance.

Simply put, Inconel 718 is an improved version of Inconel X-750. It has better performance while maintaining the same price. It can be selected first in the project.

We provide high performance Inconel 718 and Inconel X-750 materials. If you have purchasing needs, please contact us.