The basic compositions of both are almost the same. The core difference lies in the precipitation hardening ability brought about by the addition of aluminum and titanium. Monel 400 is a single-phase solution strengthened alloy, which only enhances strength through cold processing, with a yield strength of approximately 172 MPa and a tensile strength of approximately 517 MPa. After K500 is added with aluminum and titanium and undergoes aging treatment, the Ni₃(Al, Ti) strengthening phase is precipitated, and the yield strength jumps to approximately 724 MPa, with a tensile strength of about 1034 MPa, which are approximately four times and twice that of 400, respectively. In terms of corrosion resistance, both have similar resistance to seawater, hydrofluoric acid, alkaline solutions, and chloride stress corrosion cracking, because the base nickel-copper composition is the same and the precipitated phase does not significantly alter the electrochemical behavior. The difference lies in the application positioning: 400 is suitable for pipelines, heat exchangers, valve bodies, etc., for general corrosion resistance; K500 is used for components such as pump shafts, valve stems, and high-strength fasteners that need to withstand both high loads and corrosion.
Jiangsu Cunrui Metal Products Co., Ltd. We also supply Monel 400 and K500 alloy bars, which can assist users in selecting materials according to the working conditions. If you need support for comparison and selection, please contact us.