Inconel 625 alloy is a nickel-chromium alloy that is used for its
excellent fabricability, high corrosion resistance and high strength. It is
used in service temperature range from cryogenic to 1800°F. This alloy got its
strength from the stiffening effect of molybdenum and niobium on its
nickel-chromium matrix therefore the precipitation-hardening treatments are not
needed. It has resistance to a wide range of severe corrosive environments and
to high-temperature effects such as carburization and oxidation.
Inconel 625alloy is preferred for sea-water applications due to its
resistance to chloride-ion stress-corrosion cracking, high tensile strength,
high corrosion-fatigue strength and resistance to pitting & crevice
corrosion. This alloy is used as wire rope for mooring cables, submarine
auxiliary propulsion motors, exhaust ducts for Navy utility boats, propeller
blades for motor patrol gunboats, submarine quick-disconnect fittings,
submarine transducer controls, sheathing for undersea communication cables and
steam-line bellows. It has potential applications such as springs, bellows for
submerged controls, fasteners, seals, oceanographic instrument components,
flexure devices and electrical cable connectors.
This alloy is used for aerospace field due to its high creep,
tensile and rupture strength, oxidation resistance, excellent fatigue and
thermal-fatigue strength, excellent weldability and brazeability. It is widely
used in applications such as aircraft ducting systems, thrust-reverser systems,
fuel & hydraulic line tubing, bellows, heat-exchanger tubing in
environmental control systems, engine exhaust systems, resistance-welded
honeycomb structures for housing engine controls, spray bars and turbine shroud
rings. It is suitable for turbine seals, thrust-chamber tubing for rocket,
combustion system transition liners and compressor vanes.
Inconel 625 alloy has corrosion resistance under a wide range of
temperatures and pressures therefore it is preferred for chemical processing
applications. It is manufactured into a variety of components for plant
equipment due to its ease of fabrication. Its high strength allows it to be
used in thinner-walled vessels or tubing than possible with other materials,
thus improving heat transfer and saving weight. It is used in tubing,
distillation columns, transfer piping, bubble caps, reaction vessels, heat
exchangers and valves due to its combination of strength and corrosion
resistance.
Inconel 625 alloy is used for reactor-core and control-rod
components in nuclear water reactors. This alloy is highly useful in various
applications due to its excellent uniform corrosion resistance, high strength,
excellent pitting resistance in 500°F-600°F water and resistance to stress
cracking. Inconel 625 alloy is considered in advanced reactor concepts due to
its high allowable design strength at elevated temperatures between
1200°F-1400°F.
Hot-finished, cold-finished and annealed conditions are
recommended for service above 1200°F. The solution-treated condition is
recommended for components that need optimum resistance to creep or rupture.
Fine-grained material may be advantageous at temperatures up to 1500°F with
respect to fatigue strength, tensile, hardness and yield strength.
Typical tensile properties of annealed and solution-treated
material from room to elevated temperature were analyzed. The approximate
relationship between the hardness and tensile and yield strength of strip is
analyzed. Increased tensile properties for service at moderate temperature can
be obtained by cold work. Some hardening occurs in Inconel 625 alloy upon
exposure to intermediate temperatures.
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