M?ssbauer Effect Study of Room Temperature Cathodic Polarization of AISI321SS Austenitic Stainless Steel

摘要

Room temperature hydrogen charging by cathodic polarization of cold rolled AISI 321SS austenitic stainless steel in appropriate electrolytic medium leads to its decomposition to structural defects and a ferromagnetic α′-martensitic phase. The degree of decomposition, and hence the resulting products depends on hydrogen charging time with martensitic transformation yielding up to 14-22% martensite for charging periods of 30 and 96 h, respectively. Based on M?ssbauer spectroscopy measurements, the magnetically split portion of the spectra corresponding to the α′-martensite phase was resolved in terms of one Fe-site with internal magnetic field in the range of 260-265 ± 10 kOe. Both the uncharged and retained (after hydrogen charging) austenitic phases were resolved similarly at ambient and sub-ambient cryogenic temperatures. The austenitic phase in both the uncharged and charged states remained stable from ambient down to 4.2 K, where they exhibited singlet broadening suggesting weakly ferro/antifero-magnetic ordering.