A study on martensitic and austenitic steels after exposure in mercury at 573 K up to 5000 h

The chemical composition, structure and morphology of surface layers formed on stressed martensitic (F82H, MANET-II) and austenitic (316L) steel samples after exposure in static mercury with air or Ar inside the containers for 5000 and 2000 h, respectively, at 573 K have been studied by different surface analysis techniques (electron probe microanalysis (EPMA), scanning electron microscopy (SEM), reflected high energy electron diffraction (RHEED), X-ray diffraction (XRD), and secondary ion mass spectrometry (SIMS)). It has been shown that all three steels are oxidized (oxide thickness greatest on F82H and least for 316L) and covered with red HgO single crystals when air is present in the system. The oxidation of the steels and Hg can be suppressed by using Ar in the containers. Cracks have been found only at the notch roots of the 316L samples. There is no evident Hg corrosion observed.