Engineers working in extreme environments—whether aerospace, petrochemical, or subsea—regularly must choose materials that carry significant performance and cost implications. Nickel-based superalloys have become the standard answer to high-temperature oxidation, aggressive chemical exposure, and mechanical stress, but selecting the wrong alloy family or grade can result in premature failure or unnecessary cost.
Learn more about Inconel® grades, Incoloy® grades, and how their properties map to specific industrial applications below.

Common Grades & Chemical Composition

The key distinction between these two alloy families lies in their base chemistry:

  • Inconel® Alloys: Carry higher percentages of chromium and nickel (over 50%), with some grades incorporating molybdenum or niobium to enhance creep resistance at temperatures exceeding 1,000 °F.
  • Incoloy® Alloys: While still nickel-based (less than 50%), they include more iron in their composition, which reduces material costs while maintaining excellent resistance to sulfuric and phosphoric acids.

Inconel®

Common grades of Inconel® include:

  • Inconel® 600: Contains approximately 72% nickel and 15% chromium. It resists oxidation up to 2,150 °F and resists chloride stress-corrosion cracking better than many austenitic stainless steels.
  • Inconel® 601: Formulated with an aluminum addition to provide exceptional structural stability, carburization defense, and high-temperature oxidation resistance.
  • Inconel® 625: Adds molybdenum and niobium to its base composition. This combination produces exceptional resistance to pitting and crevice corrosion in seawater and marine atmospheres. The alloy maintains tensile strength above 100 ksi even after prolonged exposure to temperatures around 1,200 °F.
  • Inconel® 718: Stands out for its precipitation-hardening capability. After proper heat treatment, it achieves tensile strengths exceeding 200 ksi while retaining ductility. It remains stable from -423 °F to 1,300 °F.
  • Inconel® X-750: A precipitation-hardenable grade utilizing aluminum and titanium to deliver high corrosion and oxidation resistance alongside excellent mechanical strength up to 1,300°F.

Incoloy®

Common Incoloy® grades include:

  • Incoloy® 20: An austenitic stabilizing grade engineered specifically to resist severe corrosion in sulfuric, phosphoric, and nitric acid environments.
  • Incoloy® 800: Contains roughly 32% nickel and 21% chromium, resisting carburization and maintaining structural integrity in oxidizing atmospheres up to 1,500 °F.
  • Incoloy® 825: Incorporates molybdenum, copper, and titanium for superior resistance to sulfuric and phosphoric acids across wide concentration ranges. Typical applications include chemical processing vessels, pollution control systems, and acid production equipment.
  • Incoloy® 925: A precipitation-hardenable variant that offers better stress-corrosion cracking resistance than many precipitation-hardening stainless steels.

Key Features

Choosing between these alloy families comes down to the factors in your operating environment:

  • Extreme Heat and Thermal Cycling: Inconel® alloys maintain mechanical properties through repeated heating and cooling, resisting oxidation via self-healing chromium oxide layers. This performance profile is critical for jet engine components experiencing rapid temperature fluctuations during operation.
  • Aggressive Chemical Environments: Incoloy® alloys resist sulfidation and carburization better than austenitic stainless steels, outperforming 304 and 316 grades in petrochemical refining where sulfur compounds and carbon-rich atmospheres are present.
  • Cryogenic Applications: Incoloy® retains ductility and impact resistance down to -320 °F, so it is often used in LNG transfer lines and cryogenic processing equipment where brittle fracture is a concern.
  • Fabrication Considerations: Incoloy®’s higher iron content makes it easier to machine and weld using standard procedures. Inconel® requires specialized techniques, such as stress-relief annealing between cold-forming operations and strict cleanliness protocols during welding.

Contact Continental Steel & Tube to Learn More

Continental Steel supplies both Inconel® and Incoloy® alloys with full material certifications and traceability documentation. Both families conform to ASTM, AMS, and MIL-SPEC requirements as required and are available in sheet, plate, pipe, tube, bar, and wire forms. Our inventory includes multiple grades and forms to match your technical specifications. We quote to your exact requirements for dimensions, quantity, and compliance standards, and can provide secondary processing services upon request.

We maintain strategic distribution facilities in Texas, Florida, Ohio, and California to support tight delivery schedules across North America. International exporting services are also available for projects in South America and Europe.

Contact us at 954-332-2290 or request a quote today to get started with your order.