Influence of the aging time on the microstructure and electrochemical behaviour of a 15-5PH ultra-high strength stainless steel

The effect of the aging time at 500 °C on the microstructure evolution and electrochemical behaviour of 15-5PH ultra-high strength martensitic stainless steel is presented. The results show that Cu-rich clusters and (Cu, Nb)-rich nanoparticles are observed from 1 min to 240 min. The aging time influences the pitting resistance and semiconductive behaviour of the passive film in a chloride solution. The disappearance of Cu species in the passive film after 240 min is attributed to the precipitation of Cu-rich nanoparticles. Moreover, the variations in the Cr/Fe ratio and dehydration effect with the aging time are discussed.