Monel 400 is the most versatile and comprehensive corrosion resistant alloy. This alloy has excellent corrosion resistance in hydrofluoric acid and fluorine gas media, and also has excellent corrosion resistance to hot concentrated alkali liquids. At the same time, it is also resistant to corrosion of neutral solutions, water, seawater, atmosphere, organic compounds, etc. An important feature of the alloy is that it generally does not produce stress corrosion cracks and has good cutting performance.

Monel K500 is a precipitation-hardenable Ni-Co alloy that combines the excellent corrosion resistance characteristic of Monel 400 with the added advantage of greater strength and hardness. These amplified properties, strength and hardness, are obtained by adding AL and Ti to the Ni-Co base and by a thermal processing used to effect precipitation, typically called age hardening or aging. When in the age-hardened condition, Monel K-500 has a greater tendency toward stress-corrosion cracking in some environments than Monel 400. Alloy K-500 has approximately three times the yield strength and double the tensile strength when compared with alloy 400. Plus, it can be further strengthened by cold working prior to precipitation hardening. The strength of this nickel based alloy is maintained to 1200° F but stays ductile and tough down to temperatures of 400° F. Its melting range is 2400-2460°F.