Investigation of microstructure and thermal stability of pulsed plasma processed chromium ferritic-martensitic steels

摘要

This paper presents results of the microstructural evolution and thermal stability of the promising Russian ferritic-martensitic steels (EP 823, EP 900, EK 181 and ChS 139) for the nuclear and fusion application after surface modification by high temperature pulsed plasma flows (HTPPF) treatment. Investigations of microstructure, topography and elemental content changes associated with irradiation by nitrogen plasma with energy density 19-28 J/ cm2 and pulse duration 20 us were carried out. Changes in microstructure and elemental content occurring in the modified surface layer were characterized by means of scanning election microscopy (SEM) and X-ray microanalysis (EDS and WDS). It was shown that independently of initial microstructure and phase composition, HTPPF treatment of ferritic-martensitic steels leads to formation of ultrafine homogeneous structure in the near surface layers with typical grain size ～100 nm. Results of microstructure investigations after annealing during 1 hour demonstrates significant thermal stability of nanostructure formed by HTPPF treatment.