Cobalt L-605 (also known as alloy 25) is a cobalt-based superalloy with high levels of chromium and tungsten. It is characterized by outstanding high-temperature strength up to 1500 °F (1093 °C), excellent oxidation resistance at high temperatures up to 2000 °F (1093 °C) in corrosive environments, and superior resistance to sulfidation wear and galling. Cobalt L-605 has other less-known qualities like high ductility and biocompatibility. Cobalt L-605 is non-magnetic. Chemical Composition of Cobalt L-605 Element Min (%) Max (%) Carbon, C 0.05 0.15 Manganese, Mn — ≤ 2.00 Silicon, Si — ≤ 0.40 Sulfur, S — ≤ 0.015 Phosphorus, P — ≤ 0.02 Chromium, Cr 19.0 21.0 Molybdenum, Mo 1.20 1.40 Iron, Fe — ≤ 3.00 Tungsten, W 14.0 16.0 Nickel, Ni 9.0 11.0 Cobalt, Co — *Balance Mechanical and Physical Properties Property Imperial Metric Density 0.335 lb/in3 9.27 g/cm3 Melting Range 2425 – 2570 °F 1330 – 1410 °C Tensile Strength 154 ksi 1061 MPa Tensile Strength, Yield 0.2% 75 ksi 517 MPa Elongation in 2 inches (50 mm) 55 % 55 % Elongation A5 25 % 25 % Electrical Resistivity 34.9 µΩ in 88.6 µΩ cm Magnetic Permeability at 200 oersteds 1.002 1.002 Thermal Conductivity 65 Btu⋅in/ft2 h °F 9.4 W/m K Specific Heat 0.092 Btu/lb °F 385 J/kg °C Coefficient of Thermal Expansion, RT – 200°F 6.8 × 10-6 in/in °F 12.3 µm/m °C Resistance on air (up to the temperature listed) 1994 °F 1090 °C
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