Alloy Specification Carbon Manganese Silicon Chromium Nickel Molybdenum Tungsten Cobalt Phosphorus Sulfur Copper Iron    Other 
Co 6 AMS 5387 and  5373 0.90 to 1.40 1.00 1.50 27.0 to 31.0 3.00 1.50 3.5 to 5.50 Balance 0.04 0.03 3.00
Co 12 1.10 to 1.70 1.00 1.00 28.0 to 32.0 3.00 7.0 to 9.50 Balance 0.04 0.03 3.00
Co 21 AMS 5385 0.20 to 0.30 1.00 1.00 25.00 to 29.00 1.75 to 3.75 5.00 to 6.00 Balance 0.04 0.04 3.00
Co 25 H.S. 25 (L605) 0.05 to 0.15 1.0 to 2.0 1.0 19.0 to 21.0 9.0 to 11.0 14.00 to 16.00 Balance 0.04 0.04 3.00
Co 31 AMS 5382 0.45 to 0.55 1.00 1.00 24.5 to 26.50 9.5 to 11.50 0.5 7.00 to 8.00 Balance 0.04 0.04 2.00 Zr 0.25
N155 AMS5376 0.20 1.00 to 2.00 1.00 20.00 to 22.50 19.00 to 21.00 2.50 to 3.50 2.00 to 3.000 18.5 to 21.00 0.04 0.03 Balance Cb/Ta 0.75 to 1.25

Ta 0.05 Max

N2 0.10 to 0.20