Can Inconel be hardened?
Extreme strength and toughness are desirable qualities in industrial applications. We explore the strength properties of INCONEL alloy 725, an age-hardened material with exceptional corrosion resistance
Some industrial applications require materials of the highest strength to withstand difficult environments.INCONEL alloy 725 is one such material, with extremely high strength, achieved through precipitation hardening.
This heat treatment increases the yield strength, which produces materials that are particularly tough and strong, even in high-temperature situations. In this age-hardened condition, INCONEL alloy 725 is one of the strongest superalloys available in the GNEE group product line, as well as being both ductile and tough.
As well as the heat treatment, INCONEL alloy 725 is strong due to its balanced composition of elements. It is a nickel-chromium Grade, but it also has a significant amount of molybdenum. This essential chemical element gives excellent strength and mechanical stability to nickel alloys, which is why it is widely included.
The alloy also includes aluminium and titanium , the latter of which has the highest strength-to-density ratio of any metallic element. Both of these additions help to impart desirable strength qualities.
INCONEL alloy 725 vs 625
INCONEL alloy 725 is comparable in many ways to the popular INCONEL alloy 625 , another superalloy that is known for its high strength and versatility. Both Grades offer a similar level of excellent corrosion resistance, making them usable in some of the most severe environments. This corrosion resistance helps INCONEL alloy 725 retain its famed strength, with high resistance to hydrogen embrittlement and stress corrosion cracking – two factors that could otherwise negatively affect a material's continued strength.
The inclusion of nickel and chromium provides resistance to both reducing and oxidising environments, while the aforementioned molybdenum boosts its resistance to reducing media, as well as giving some protection against pitting and crevice corrosion.
INCONEL alloy 725 was developed from INCONEL alloy 625, building on its already impressive base, and adding in the addition of elements and treatments to enhance its mechanical properties to offer even higher strength. As such, it is around twice as strong as annealed INCONEL alloy 625.
