Study of nobility of chromium nitrides in isothermally aged duplex stainless steels by using SKPFM and SEM/EDS

摘要

The relative nobility of Cr_2N in duplex stainless steels (DSSs) was investigated in isothermally aged 2205 and 2507 DSSs using scanning Kelvin probe force microscopy (SKPFM) and SEM/EDS. The specimens contained nitrides, austenite and sigma phase but no ferrite. In these materials, Cr_2N exhibits a higher Volta potential than sigma phase and austenite, implying the highest practical nobility of Cr_2N compare to the surrounding phases. The composition and alloying effect can explain the relative nobility of the phases. The apparent "size effect" of small Cr_2N on the measured Volta potential difference is probably due to the influence of surrounding matrix.