Conclusions
From a qualitative point of view both techniques (DL-EPR test and PD) agree in the determination of the relative variation of the localised corrosion susceptibility of the studied materials.
In addition the results obtained for the conventional SS (AISI304con) are quantitatively in good agreement, in fact the ratio between the DOS increase percentages obtained for the two samples at different heat treatment times (0.5 and 5 hours) are 3.74 and 3.91 for the EPR and PD measurements, respectively.
A remarkable improvement to withstand localised corrosion when 304 SS is heated in the sensitization temperature range is obtained through the optimisation of grain boundary structure. The 304 SS subjected to the thermomechanical process allows a reduced precipitation of carbides and thus an improved resistance to localised corrosion.