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What are nickel alloys used for?
Short answer
Nickel alloys are used where stainless steel cannot cope: hot concentrated acids, severe chlorides, sour gas, very high temperatures and seawater-critical parts. The main families are Inconel (Ni-Cr), Incoloy (Fe-Ni-Cr), Monel (Ni-Cu), Hastelloy (Ni-Mo-Cr) and commercially pure nickel.
Nickel-chromium (Inconel family)
Iron-nickel-chromium (Incoloy family)
Nickel-copper (Monel family)
Nickel-molybdenum-chromium (Hastelloy family)
Commercially pure nickel
Nickel 200 and SS 201 are used for caustic soda, food processing and electronics. SS 201 is the low-carbon version for use above about 315 °C.
Trade names and generic alloys
Inconel, Incoloy and Monel are Special Metals trademarks, and Hastelloy is a Haynes International trademark. Generic material produced to the same ASTM/ASME specification is identified by UNS number, for example Alloy 625 = UNS N06625. Order by specification and UNS to get what the design requires.
Choosing a nickel alloy family
| Need | Family | Typical alloys |
|---|---|---|
| High-temperature oxidation | Ni-Cr / Fe-Ni-Cr | 601, 800HT |
| Seawater + strength | Ni-Cr-Mo | 625 |
| Sulphuric acid, sour gas | Fe-Ni-Cr-Mo-Cu | 825 |
| HF acid, seawater shafts | Ni-Cu | 400, K-500 |
| Severe mixed chemicals | Ni-Mo-Cr | C276, C22 |
| Caustic soda | Pure Ni | 200, SS 201 |
Why nickel helps
Nickel keeps the alloy austenitic and tough, resists chloride stress-corrosion cracking far better than iron-based alloys, and dissolves large amounts of chromium and molybdenum. That lets designers add the corrosion-resisting elements stainless steel cannot hold in solution.
Choosing a family quickly
Materials in this guide
Related guides, comparisons and articles
Frequently asked questions
Are nickel alloys and superalloys the same?
Many high-temperature nickel alloys, such as 718, are called superalloys. The term usually refers to alloys designed for strength at high temperature.
Why are nickel alloys so expensive?
Nickel and molybdenum are costly raw materials, and the alloys are harder to melt, work and machine.
Is Inconel better than stainless steel?
For severe corrosion or high temperatures, yes, but at several times the cost. Stainless steel is the economical choice wherever it performs adequately.
How do I choose between grades?
Start from the service environment (chlorides, acids, temperature, pressure), then check the governing code and cost. Our comparisons and grade pages list typical choices, and our team can help shortlist grades for your conditions.
Does Bright Tubes supply the materials in this guide?
Yes. Inconel 600, Inconel 601, Inconel 625, Inconel 718, Incoloy 800, Incoloy 800H and related products are supplied from stock or mill-sourced, with EN 10204 certificates.