What is the chemical composition of Inconel 625?

UNS N06625 / W.Nr. 2.4856: nickel balance, 20-23% chromium, 8-10% molybdenum and 3.15-4.15% niobium plus tantalum.

How does 625 get its strength without heat treatment?

The niobium and molybdenum stiffen the solid-solution matrix, giving high strength in the annealed condition.

What are its mechanical properties?

Tensile about 930 MPa (135 ksi), yield about 517 MPa (75 ksi) and 42.5% elongation.

What are typical applications?

Aerospace ducting, chemical processing, marine engineering and nuclear components.

What standards cover 625?

UNS N06625 / W.Nr. 2.4856, with ASTM B446 and AMS 5666 covering bar and shapes.

Is Inconel 625 weldable?

Yes - it is one of the most weldable nickel alloys, with the niobium preventing sensitization.

Round bar, plate, sheet, tube, pipe, wire, forgings and welding filler.

It resists a wide range of severely corrosive environments and is especially resistant to pitting and crevice corrosion.

Inconel is a registered family of nickel-chromium-based superalloys characterised by high strength and oxidation resistance at elevated temperature.

Which Inconel grade should I choose for high temperature?

Inconel 601 for oxidation up to about 1250 C, Inconel 617 and 625 for creep-limited service, and Inconel 718 where high tensile and fatigue strength up to about 650 C is required.

Which Inconel is best for sour gas (H2S) service?

Age-hardenable grades Inconel 718 and Inconel 725 are the standard choices for sour-gas downhole tubing and wellhead components under NACE MR0175 / ISO 15156.

Most Inconel grades are fully austenitic and non-magnetic in the annealed condition; cold work can produce slight magnetism in some grades.

Can Inconel be welded?

Yes. Most grades are welded with matching or over-alloyed nickel filler metals under AWS A5.14 (for example ERNiCrMo-3 for 625, ERNiCr-3 for 600/601, ERNiFeCr-2 for 718).

Nickel Alloy Families: Complete Grade Index

Quick Answer

Which nickel alloy family do I need?

Choose Inconel for high-temperature strength, Hastelloy for aggressive chemical corrosion, Monel or copper-nickel for seawater, Incoloy for cost-effective heat resistance, pure nickel for caustic service, and cast superalloys for turbine hot-section components.

How do I choose between alloy families?

Service condition	Recommended family	Reason
High temperature > 600 °C in air	Inconel / Incoloy	Chromia or alumina scale gives oxidation and creep resistance
Hydrochloric or sulfuric acid	Hastelloy (B / C / G series)	Molybdenum and chromium control reducing and oxidizing acid attack
Seawater, brine, hydrofluoric acid	Monel / Copper-nickel	Nickel-copper chemistry resists chloride and biofouling
Caustic soda and alkalis	Pure nickel (200 / 201)	Commercially pure nickel is the reference material for caustic evaporators
Sour gas (H2S) downhole	Age-hardenable Inconel / Incoloy	Meets NACE MR0175 / ISO 15156 at high strength levels
Gas turbine blades and vanes	Cast nickel superalloys	Investment-cast creep and hot-corrosion resistant compositions

What product forms are available?

Round bars · Seamless tubes · Plates & sheets · Precision strips · Forgings & rings · Welding wire. Supplied to ASTM, ASME, AMS, DIN/W.Nr., EN, GB and GOST with EN 10204 3.1 / 3.2 certification.

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Nickel Alloy Families: Complete Grade Index

Which alloy families are covered?

Inconel Alloys

Hastelloy Alloys

Monel Alloys

Incoloy Alloys

Pure Nickel Grades

Copper-Nickel Alloys

Cast Nickel Superalloys

How do I choose between alloy families?

What product forms are available?

Nickel Alloy Families: Complete Grade Index

Which alloy families are covered?

Inconel Alloys

Hastelloy Alloys

Monel Alloys

Incoloy Alloys

Pure Nickel Grades

Copper-Nickel Alloys

Cast Nickel Superalloys

How do I choose between alloy families?

What product forms are available?

Related Alloy Knowledge