Alloy 725 (UNS N07725), commonly known as Inconel 725, is a nickel chromium-molybdenum-niobium alloy that is highly resistant to corrosion and is age hardenable for extremely high strength. It has essentially the same corrosion resistance as alloy 625, which is widely used in a broad range of severely corrosive environments in the oil & gas sector. The strength of age-hardened alloy 725 is of the order of twice that of annealed Alloy 625. Alloy 725 exhibits a high resistance in reducing and oxidizing environments and increased resistance to pitting and crevice corrosion in sea water and stress corrosion cracking. Because the strength of alloy 725 is developed by heat treatment, not by cold work, ductility and toughness remain high.
The properties of alloy 725 are useful for a range of applications that require outstanding corrosion resistance along with high strength. The alloy is used for hangers, landing nipples, side pocket mandrels and polished bore receptacles in sour gas service, where it resists the effects of hydrogen sulfide, chlorides and carbon dioxide. The alloy is also attractive for high strength fasteners in marine applications, where it resists corrosion, pitting and crevice attack in sea water. vSM stocks Alloy 725 bars between 0.5 – 12.0 dia.
The data above based on age hardening condition
| Carbon(C) | Manganese(Mn) | Phosphorus(P) | Sulfur(S) | Silicon(Si) | Nickel(Ni) | Cobalt(Co) |
| 0.03 Max | 0.35 Max | 0.015 Max | 0.010 Max | 0.20 Max | 55.00%-59.00% | — |
| Chromium(Cr) | Molybdenum(Mo) | Niobium (Columbium)Nb | Titanium(Ti) | Copper(Cu) | Aluminum(Al) | Iron (Fe) & Others |
| 19.00%-22.50% | 7.00%-9.50% | 2.75%-4.00% Max | 1.00%-1.70% | — | 0.35 Max | RemainderFe Balance |