Effect of Isothermal Solidification and Chloride Concentration on Pitting Corrosion Resistance of TLP Bonded ۲۲۰۵ Duplex Stainless Steel

In the present study, the effect of completion of isothermal solidification (IS) and NaCl concentration on potentiodynamic polarization behavior (PDP) of transient liquid phase bonded (TLP) ۲۲۰۵ duplex stainless steel (DSS) was investigated. The PDP results indicated that the pitting potential was decreased from ۱.۱۷۱VAg/AgCl in the as-received base metal to ۰.۳۷۳VAg/AgCl in the TLP bonded specimen before completing the IS in ۰.۱M NaCl test solution. By completion of the IS, the pitting potential of TLP bonded specimen increased to ۱.۱۸۰VAg/AgCl which was similar to that of the as-received base metal (۱.۱۷۱VAg/AgCl). This improve of pitting potential was strongly related to the uniform distribution of Cr and Mo across the bonding zone due to removing (Mo, Cr)-rich secondary phases from the bonding zone after completion of the IS. Before completion of the IS, the pitting potential of TLP bonded specimen decreased significantly with the increasing chloride concentration, while after it, the pitting potential was almost equal to that of the as-received base metal until ۱.۵M NaCl, but with increasing to ۲.۵M NaCl, the stable pitting attack occurred in the bonding zone and therefore, the pitting potential was decreased in the TLP bonded specimen. Furthermore, with increasing chloride concentration from ۰.۱ to ۲.۵M, the pitting corrosion was extended in the bonding zone before completing the isothermal solidification, which could be due to decreasing the pitting potential of TLP bonded specimen with increasing the NaCl concentration.

Keywords:

۲۲۰۵ DSS , TLP , Isothermal Solidification , Pitting potential , Concentratio , ۲۲۰۵ , DSS , TLP , انجماد همدما , خوردگی حفره ای , غلظت