# Alloy 188 (UNS R30188) High-Temperature Cobalt-Based Superalloy
Introduction to Alloy 188
Alloy 188, also known as UNS R30188, is a high-temperature cobalt-based superalloy renowned for its exceptional strength and oxidation resistance at elevated temperatures. This alloy is specifically designed to withstand extreme environments, making it a preferred choice for aerospace, industrial gas turbines, and other demanding applications.
Chemical Composition
The unique properties of Alloy 188 stem from its carefully balanced chemical composition:
- Cobalt (Co): 37-43%
- Chromium (Cr): 20-24%
- Nickel (Ni): 20-24%
- Tungsten (W): 13-15%
- Iron (Fe): ≤3%
- Manganese (Mn): ≤1.25%
- Silicon (Si): ≤0.4%
- Carbon (C): 0.05-0.15%
- Lanthanum (La): 0.03-0.12%
Keyword: Alloy 188 UNS R30188
Key Properties
High-Temperature Strength
Alloy 188 maintains excellent mechanical properties at temperatures up to 2000°F (1093°C), outperforming many nickel-based alloys in this temperature range.
Oxidation Resistance
The chromium content provides outstanding oxidation resistance, while the lanthanum addition enhances scale adhesion and further improves high-temperature oxidation resistance.
Thermal Stability
This alloy demonstrates remarkable thermal stability, resisting thermal fatigue and maintaining its properties through repeated thermal cycling.
Applications
Alloy 188 finds extensive use in various high-temperature applications:
- Aerospace components (combustion chambers, afterburners)
- Industrial gas turbine components
- Heat treatment fixtures
- Chemical processing equipment
- Nuclear reactor components
Fabrication and Welding
Alloy 188 can be fabricated using standard techniques, though its high strength requires more power than conventional alloys. It welds well using matching filler metals and proper techniques to maintain its corrosion resistance.
Conclusion
Alloy 188 (UNS R30188) stands as a premier cobalt-based superalloy for extreme temperature applications. Its combination of high-temperature strength, oxidation resistance, and thermal stability makes it invaluable in aerospace and industrial applications where performance under stress at elevated temperatures is critical.
