The strength of age-hardened INCONEL alloy 725
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 Corrotherm product line, as well as being both ductile and tough.
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.
Industrial applications
A material with this high level of corrosion resistance, strength, ductility and toughness can be employed in a vast number of different situations. It is often used for tubing hangars, landing nipples, side pocket mandrels, polished bore receptacles and high-strength fasteners.
One of its prime uses is in the sour gas industry, where it exhibits corrosion resistance against the effects of hydrogen sulfide, chlorides and carbon dioxide, retaining its strength in these toxic conditions. It is also well used in marine applications, as it can resist against pitting and crevice attack in seawater.
There is an even higher-strength version of INCONEL alloy 725, alloy 725HS. This material has the same excellent corrosion resistance as its base material, but it offers 2.3 times the strength of annealed INCONEL alloy 625 and has around 20ksi higher yield strength than the standard INCONEL alloy 725. This is achieved by optimising the age-hardening treatment and grain refinement. This material is useful for components in ship construction where the seawater resistance is essential, but also exceptionally high strength is required.
Find out more about INCONEL alloy 725 by getting in touch with a member of our team. Contact us today .
