Alloy 725 (UNS N07725)

Alloy 725

Alloy 725 (UNS N07725) 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.

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Alloy 725 Specification/Condition

• API 6ACRA / NACE MR0175, UNS N07725

Alloy 725 Applications

• Landing nipples
• Hangers
• Side pocket mandrels
• Polished bore receptacles (PBRs) in sour service environments
• Fasteners in marine environments
• Hydraulic couplings
• Pumps and propeller shafts

Alloy 725 Technical Data – in 120K material designation Age Hardened – to API 6ACRA

• UTS (KSI): min 150ksi
• Yield 0.2% Offset (KSI): min 120ksi- max 150ksi
• EL (% Min): 20%
• RA (% Min): 35% (Less than 10” QTC), 25% (Greater than or Equal to 10” QTC)
• Hardness (BHN): Max 393BHN

The data above based on age hardening condition

Stocking Dimensions

• Bar: 0.5 – 12.0 dia
• Bored Bar with bespoke internal diameters via vSM’s in-house deep hole drilling and honing capabilities

Alloy 725 Chemical Composition (Wt %)

 

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	Remainder Fe Balance