Haynes 188 (UNS R30188): Cobalt Superalloy for Combustion Chambers

AMS 5608 / ASTM B435 · Published: 2026-06-02 · Updated: 2026-06-02

Quick Reference

Haynes 188: cobalt-base superalloy with exceptional oxidation resistance to 1,095°C and outstanding post-aging ductility — retains 15-20% elongation after 1,000+ hours at 870°C. For military and commercial engine combustor liners, transition...

Haynes 188: cobalt-base superalloy with exceptional oxidation resistance to 1,095°C and outstanding post-aging ductility — retains 15-20% elongation after 1,000+ hours at 870°C. For military and commercial engine combustor liners, transition ducts, afterburner flame holders. Cobalt resists sulfidation from jet fuel sulfur.

Quick Facts

CategoryNickel Alloy
StandardAMS 5608 / ASTM B435
Density9130 kg/m³
Yield Strength450 MPa
Tensile Strength950 MPa

Global Equivalents & Cross-Reference

Alternative Standard / GradeAction
UNS R30188 Compare
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Frequently Asked Questions

Why cobalt not nickel for combustors?

Cobalt retains ductility after long-term exposure (nickel forms embrittling TCP phases). Better sulfidation resistance from jet fuel.

References & International Standards

  • ASTM International. Standard Specifications for Steel & Metal Alloys. astm.org
  • International Organization for Standardization (ISO). Metallic Materials — Cross-Reference Database. iso.org
  • American Iron and Steel Institute (AISI). Steel Grade Designations & Equivalents. steel.org
  • European Committee for Standardization (CEN). EN Steel Standards & Numbering System. cencenelec.eu