Technical guide · 2026-08-14
Cobalt-Base Superalloys
Cobalt-base superalloys combine solid-solution and carbide strengthening with hot-corrosion resistance for combustor and furnace components, requiring product-route, grain and heat-treatment controls rather than a generic temperature rating.
01
Definition and boundary
Covers load-bearing high-temperature cobalt alloys; excludes nickel-base superalloys and wear overlays whose primary function is surface life.
Reference information only: final acceptance is controlled by the ordered product specification, condition, dimensions and certified test results.
02
How the material system works
Cobalt matrix retains hot strength.
Chromium resists oxidation and hot corrosion.
Carbides stabilize grain boundaries.
03
Representative grades and systems
| Grade or system | Selection focus | Qualification |
|---|---|---|
| Haynes 188 | Wrought Co-Ni-Cr-W sheet alloy. | Confirm the governing product specification, delivery condition, section size and acceptance tests before treating designations as interchangeable. |
| MAR-M 509 | Cast cobalt turbine alloy. | Confirm the governing product specification, delivery condition, section size and acceptance tests before treating designations as interchangeable. |
| L-605 / Alloy 25 | Wrought high-temperature Co-Cr-W-Ni alloy. | Confirm the governing product specification, delivery condition, section size and acceptance tests before treating designations as interchangeable. |
04
Properties and trade-offs
Creep strength
Thermal-fatigue resistance
Oxidation/hot-corrosion resistance
05
Product forms and supply conditions
06
Applications and selection
Applications and selection
- Combustor liners
- Transition ducts
- Furnace fixtures
Properties and trade-offs
- Use time-temperature-stress history.
- Separate cast and wrought capability.
- Review sulfur and deposit chemistry.
07
Fabrication, durability and inspection
Control solution heat treatment.
Qualify weld repair and filler.
Protect surfaces from contamination.
08
Procurement checklist
- State alloy and cast/wrought form.
- Define melt route, grain and heat treatment.
- Specify creep/fatigue tests, NDT and weld-repair limits.
09
Standards, sources and review
Standards and designation context
- Applicable ASTM or ISO product scope
- Buyer drawing and service qualification
- Agreed inspection and certification plan