The influence of the microstructure on the resistance to pitting potential in austenitic stainless steel UNS
N31603 is evaluated to explain the effect of the distribution of features such as carbides. Different
microstructures were obtained by processing, via surface laser melting (SLM) and sensitized at 600°C,
700°C and 800°C. The test solution used for electrochemical testing included a pH 8 brine at room
conditions.

The characterization of the passive conditions is done by using potentiodynamic, potentiostatic and Mott
Schottky techniques. The results show that the UNS N31603 samples produced by SLM have higher passive layer stability. The correlation with the microstructural features attribute this to a lack of inclusions
and carbides characteristic of the SLM process. The analysis of the experimental results using the point
defect model description of the passive layer behavior indicates that the stability of the passive layer is a
priori inversely proportional to both the metal cation and anion vacancy diffusivities.