Combined effects of irradiation and hydrogen on the mechanical and corrosion performances of the ferrite in duplex phase steels

•The mechanical and corrosion behavior of the ferrite in peak damaged region (PDR) was firstly studied.•The irradiation-induced hardening of PDR was attenuated due to the potential presence of hydrogen.•The oxidation of PDR was promoted by the hydrogen enrichment.•Compared with the ferrite on UDR and UR, that on PDR shows a lowest EWF. Structural materials in nuclear reactor cores suffer from severe corrosion and weakened mechanical properties under the combined influences of hydrogen and irradiation. In this study, we studied the peak damaged region (PDR) in the ferrite phase of a duplex stainless steel post proton irradiation, which is featured with a relatively higher concentration of hydrogen and level of irradiation damages than that of the uniformly damaged region (UDR). It is found that the irradiation-induced hardening effect is more evident in UDR than in PDR, and the PDR exhibits a much larger drop of electron work function and worse corrosion resistance than the UDR. Moreover, the oxide film on the PDR shows a much lower electrical resistivity than that of the UDR. The degradation of mechanical performance and corrosion resistance is associated with the local enrichment of hydrogen and the formation of G-phase in the PDR under the unique combined influence of hydrogen and irradiation. This study sheds lights on the synergetic effects of hydrogen and irradiation on the degradation of steels in reactor cores. [Display omitted] (a–e) show the H distribution characterized by SIMS and HMT techniques; (f) shows the SRIM simulations on irradiation damage distribution in the sample depth direction; (g) and (h) show the etching-induced topography changes and 3D compositional information of the oxide film characterized by AFM and SIMS, respectively.