ALLOY 725
NICKEL & SUPER ALLOYS
API 6A CRA (UNS N07725)
GENERAL SCOPE
Alloy 725 is highly resistant to corrosion and is age hardenable for extremely high strength. It is used in a broad range of severe corrosive environments. The strength of age-hardened A725 is twice that of A625 annealed. Strength in A725 is obtained by heat treatment and can also be cold worked for even higher strength. There is also a high resistance in reducing and oxidizing environments and increased resistance to pitting and crevice corrosion in seawater and stress corrosion cracking.
Due to outstanding corrosion resistance and high strength, applications for this alloy are used for hangers, side pocket mandrels, springs and polished bore receptacles for sour gas service. The petrochemical and processing industries are good candidates for this alloy. A725 is also used for high-strength fasteners in marine applications to resist corrosion, pitting and crevice attack in sea water.
A hardness level of 43 HRC max. is allowed in NACE MR0175, 44 HRC Max is allowed when elemental sulphur is not present.
CHEMICAL COMPOSITION
| C | Si | Mn | P | S | Cr | Ni | Mo | nbCb | Ti | AI | Fe | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Min | . | . | . | . | . | 19.00 | 55.00 | 7.00 | 2.75 | 1.00 | . | 0.00 |
| Max | 0.03 | 0.20 | 0.35 | 0.015 | 0.010 | 22.50 | 59.00 | 9.50 | 4.00 | 1.70 | 0.35 | 0.00 |
MECHANICAL PROPERTIES
| U.T.S | 150 KSI Min | |
| 0.2% Proof Stress | 120 KSI Min | 150 |
| Elongation | 20 % | |
| Reduction of Area | 35 % |