Haynes 188 is a cobalt-based alloy which possesses a unique combination of properties. It has excellent high temperature strength and oxidation resistance to 2100°F (1150°C) combined with good post-aging ductility.
Alloy 188 has average room temperature tensile properties in the bright annealed condition of 137.2 ksi (946 MPa) ultimate strength, 67.3 ksi (464 MPa) yield strength and 53% elongation. At 1800°F (980°C) the alloy has ultimate and yield strengths of 35.2 ksi (243 MPa) and 19.0 ksi (131 MPa), respectively, with 59% elongation. Cryogenic temperatures do not significantly affect the ductility of alloy 188, but strength levels are increased markedly.
The excellent oxidation resistance of Haynes 188 results from minute additions of lanthanum, which modifies the protective oxide scale in such a manner that the oxide becomes extremely tenacious and retards diffusion when exposed to temperatures through 2100°F (1150°C).
Haynes 188 exhibits good ductility after prolonged exposure at temperatures of 1200, 1400, and 1600°F (650, 760 and 870°C) for 16,000 hours.