Why engineers specify Inconel 625

01

Seawater and chloride corrosion

Essentially immune to chloride stress-corrosion cracking — the go-to for subsea oil & gas components.

02

High-temperature strength retention

Retains full structural capability at 650 °C; still useful at 980 °C for non-structural exhaust ducting.

03

Oxidation and sulfidation resistance

Flue-gas service, incinerator components, and petrochemical cracking equipment.

§01 Chemical composition

ElementContent
Nickel58% min
Chromium20–23%
Molybdenum8–10%
Niobium + Tantalum3.15–4.15%
Iron (max)5%
Carbon (max)0.10%

Composition per ASTM B446. Specific mill test reports (MTR) available on request for production orders.

§02 Typical applications

Subsea wellhead components
Aerospace exhaust systems
Chemical reactor internals
Marine propeller shafts
Flue-gas scrubbers
Bellows and expansion joints

§03 Design considerations

Machinability is 11% — slow and expensive

Budget 3–4× the machining time vs 316 stainless. Ceramic tooling or carbide at very low speed with high feed.

Work hardens aggressively

Never dwell in cut. Every pass must take a proper chip — rubbing creates a hardened skin that destroys the next tool.

Consider alternatives for non-severe service

If actual service is below 400 °C and not seawater, super-duplex stainless (2507) may deliver 80% of the corrosion performance at 30% of the cost.

READY TO MACHINE INCONEL 625

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