Inconel® Alloy 625™ is a nickel chromium molybdenum alloy with high
strength at elevated temperatures, combined with outstanding
corrosion resistance. It has the best all-round combination of
strength, high temperatures and corrosion resistance of the Inconel
family of alloys. It is pre-qualified for use in pressure vessels
up to 815°C. Inconel 625LCF is a special quality of the alloy for
use in bellows. Chemical CompositionASTM B446 – Bar Element | Inconel® 625™ | Inconel® 625LCF™ | Nickel | 58.0 min | 58.0 min | Chromium | 20.0-23.0 | 20.0-23.0 | Molybdenum | 8.0-10.0 | 8.0-10.0 | Niobium + Tantalum | 3.15-4.15 | 3.15-4.15 | Iron | 5.0 max | 5.0 max | Cobalt (if determined) | 1.0 max | 1.0 max | Manganese | 0.50 max | 0.50 max | Carbon | 0.10 max | 0.03 max | Nitrogen | – | 0.02 max | Silicon | 0.15 max | 0.15 max | Phosphorus | 0.015 max | 0.015 max | Sulphur | 0.015 max | 0.015 max | Aluminium | 0.40 max | 0.40 max | Titanium | 0.40 max | 0.40 max |
Specified Minimum Mechanical PropertiesASTM B446 – Bar | 0.2% Proof Stress | Tensile Strength | Elongation | MPa | MPa | % | Grade 1 (Annealed) | Up To 102mm | 415 | 830 | 30 | 103 to 254mm | 345 | 760 | 25 | Grade 2 (Solution Annealed) | All | 275 | 690 | 30 |
Typical Applications for Inconel AlloyChemical plant, bellows, submerged marine components, weld
overlays, power station scrubber systems, general corrosion
applications for aggressive environments, combustion and ducting
systems, fuel nozzles, after burners, aerospace components. DescriptionInconel 625 is a nickel chromium molybdenum solid solution
strengthened high strength alloy, which retains strength to high
temperatures. It is used from cryogenic temperatures to 980°C.
Fatigue strength is outstanding, particularly as the bellows grade,
Inconel 625LCF, where carbon, silicon and nitrogen are controlled
to low levels. The alloys have good oxidation resistance and resist
corrosion by many corrosive media. When exposed to high
temperatures for long periods, Inconel 625 will age harden due to
the niobium, titanium and aluminium additions. When aged there is
an increase in strength and some loss of ductility and toughness. Availability of InconelAustral Wright Metals can supply Inconel 625 as plate, sheet and
strip, rod and bar, seamless and welded tube and pipe, welding
fittings, forgings and forging billet. Inconel 625LCF is available
as annealed sheet and strip from 0.13 mm to 2.54 mm thick, up to
1219 mm wide. Pressure VesselsAS1210 prequalifies Inconel 625 up to 625°C as flat products, and
650°C as bar and forgings. ASME Boiler & Pressure Vessel Code,
Section VIII (Code Case 1409-5) allows annealed material to be used
to 650°C, solution treated to 815°C. Corrosion Resistance of InconelInconel 625 has corrosion resistance to many environments. In mild
environments such as atmosphere, fresh water and sea water, neutral
salts and alkaline media there is almost no attack. In more
aggressive media nickel and chromium resist oxidising attack, while
nickel and molybdenum resist reducing environments. Molybdenum
provides exceptional resistance to pitting and crevice corrosion,
and niobium stabilises against sensitisation and intergranular
corrosion. The nickel content makes Inconel 625 essentially free
from chloride ion stress corrosion cracking. Inconel 625 also has
excellent corrosion fatigue properties. Please consult Austral
Wright Metals for specific advice on using Inconel metal for your
application. Corrosion Rates (mm/year) in a Municipal Waste Incineratorat 650-700°C after 2050 hours and 6750 hours Alloy | 2050 hours | 6750 hours | Inconel 625 | 7 | 13 | Incoloy 800 | 35 | Destroyed | Incoloy 825 | 127 | Destroyed |
| Alloy | 2050 hours | 6750 hours | SS310 | 48 | 89 | SS316 | 71 | Destroyed | SS446 | 82 | 54 |
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Equivalent SpecificationsCountry | Body | Grade | USA | UNS | N06625 | France | AFNOR | NC 22 D Nb | GB | BS | NA21 | Germany | DIN | 2.3856 |
FabricationInconel 625 was developed for hot strength, so resists hot working.
It is ductile and can be readily hot worked with high forces. The
alloy can also be cold formed with heavy forces. Intermediate
annealing may be needed. MachinabilityInconel 625 is difficult to machine (class D-2). Heavy machines,
sharp tools, slow speeds and deep uninterrupted cuts to remove the
work hardened layer are needed. WeldabilityInconel 625 is readily welded by GMAW (MIG), GTAW (TIG), SMAW
(manual) and SAW processes. Preheat, post heat and post weld heat
treatment are not required. The area around the weld must be clean
to prevent contamination of the weld pool. Argon shielding gas is
used. | Normal Service | Higher Strength | Best Corrosion Resistance | Welding Electrode | Inconel WE 112 | N/A | Inco Weld WE 686CPT | Filler Metal | Inconel FM 625 | Inco Weld FM725NDUR | Inco Weld FM 686CPT | Flux Cored Wire | Inco Cored 625DH | N/A | N/A |
Heat TreatmentInconel 625 is annealed at 925–1040°C, cooling rate not critical.
Solution anneal at 1090–1200°C. Stress relief, if required, is at
590–760°C, or up to 870°C for complete relief. Physical Constants and Thermal PropertiesInconel 625 and 625LCF, Annealed Property | Metric Units | Density | 8,440 k g/m³ @ 20°C | | | Melting Point | 1290-1350°C | | | Electrical Resistivity | 1.29 micro-ohm . m @ 20°C | Electrical Conductivity | 1.3 % IACS @ 20°C | | | Specific Heat | 410 J/kg . °C @ 20°C | Mean Coefficient of Expansion | 12.8 x 10-6 / °C @ 20°C | Thermal Conductivity | 9.8 W / m . °C @ 20°C | Curie Temperature | <-196 @ 20°C | | | Annealed | | Modulus of Elasticity | | Tension | 208 GPa @ 20°C | Torsion | 81.4 GPa @ 20°C | Poisson’s Ratio | 0.278 @ 20°C | | | Solution Treated | | Modulus of Elasticity | | Tension | 205 GPa @ 20°C | Torsion | 77.9 GPa @ 20°C | Poisson’s Ratio | 0.312 @ 20°C |
ASTM Product SpecificationsSpecification | Title | B366 | Factory Made Wrought Nickel and Nickel Alloy Fittings | B443 | Nickel Chromium Molybdenum Columbium Alloy (UNS N06625) Plate,
Sheet and Strip | B444 | Nickel Chromium Molybdenum Columbium Alloys (UNS N06625) Pipe and
Tube | B446 | Nickel Chromium Molybdenum Columbium Alloys (UNS N06625) Rod and
Bar | B564 | Nickel Alloy Forgings | B704 | Welded UNS N06625 and UNS N08825 Alloy Tubes | B705 | Nickel Alloy (UNS N06625 and N08825) Welded Pipe | B751 | General Requirements for Nickel and Nickel Alloy Welded tube |
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