MICROSTRUCTURE AND CORROSION BEHAVIOR OF A NITROGEN ALLOYED STAINLESS-STEEL

The corrosion behaviour of a nitrogen alloyed stainless steel is inves tigated using potentiodynamic anodic polarization in physiological NaC l solution. The microstructure of forged samples is determined by micr oscopy and hardness measurements. The steel shows a globular austeniti c structure. In the zone of large forging deformation the grains are e longated. Precipitates are observed in which chromium and molybdenium are enriched. The breakdown potentials range from 200 to 1170 mV vs. S CE, most of the values exceed 500 mV. The breakdown potentials decreas e with increasing aspect ratio of the grains and increasing hardness. The precipitates are initial sites for pitting and crater shaped metal dissolution.