Technical guide · 2026-08-14
Nickel-Chromium Alloys
Nickel-chromium and nickel-chromium-iron alloys use chromium for oxidation resistance and nickel for matrix stability, supporting furnace, heat-treatment and selected corrosive duties from Alloy 600 to Alloy 800-series systems.
01
Definition and boundary
This category is chromium-led for oxidation and general high-temperature resistance; severe reducing-acid service usually demands molybdenum-bearing Ni-Cr-Mo alloys.
Reference information only: final acceptance is controlled by the ordered product specification, condition, dimensions and certified test results.
02
How the material system works
Chromium forms a protective oxide in suitable atmospheres.
Nickel stabilizes the austenitic matrix across a broad temperature range.
Carbon and grain-size controls affect creep performance in H/HT variants.
03
Representative grades and systems
| Grade or system | Selection focus | Qualification |
|---|---|---|
| Alloy 600 / UNS N06600 | Ni-Cr alloy for oxidation, caustic and selected nuclear service. | Confirm the governing product specification, delivery condition, section size and acceptance tests before treating designations as interchangeable. |
| Alloy 601 / UNS N06601 | Aluminum-bearing grade for enhanced oxidation resistance. | Confirm the governing product specification, delivery condition, section size and acceptance tests before treating designations as interchangeable. |
| Alloy 800H/800HT / UNS N08810/N08811 | Controlled carbon and grain structure for high-temperature strength. | Confirm the governing product specification, delivery condition, section size and acceptance tests before treating designations as interchangeable. |
04
Properties and trade-offs
Oxidation resistance
Thermal stability
Grade-dependent creep and rupture strength
05
Product forms and supply conditions
06
Applications and selection
Applications and selection
- Furnace fixtures and radiant tubes
- Heat-treatment baskets
- Steam-generator and process components
Properties and trade-offs
- Specify atmosphere including sulfur, carbon activity and cycling.
- Separate oxidation limit from load-bearing creep limit.
- Use the exact 800, 800H or 800HT designation and condition.
07
Fabrication, durability and inspection
Remove shop contaminants before heating.
Control solution annealing to preserve required grain structure.
Qualify dissimilar weld filler and thermal expansion mismatch.
08
Procurement checklist
- State maximum and continuous temperature with applied stress.
- Define chemistry variant, grain-size or heat-treatment requirements.
- Specify creep data basis, weld procedure and certification.
09
Standards, sources and review
Standards and designation context
- UNS designation plus exact ASTM B-series product specification
- Applicable ASME construction code
- Qualified welding and heat-treatment procedure
Authoritative research sources
Nickel Institute · Technical overview, accessed 2026
Nickel Institute · Technical Guide 11012, revised edition
Nickel Institute · Technical Guide 393, 2021