Effect of chemical passivation treatment on pitting corrosion resistance of AISI 410 and 17-4 PH stainless steels

The susceptibility of stainless steels to pitting corrosion is an essential characteristic of these alloys, since this kind of phenomenon may affect the mechanical integrity of the material and consequently cause unexpected failures. In order to avoid or minimize this localized corrosion process it is possible to enhance the protective capacity of the passive layer from the stainless steels and one of the methods to obtain this result is the chemical passivation treatment. In this context, the effect of the passivation treatment with nitric acid on pitting corrosion resistance of the AISI 410 and 17–4 PH stainless steels in chloride containing media is investigated. For this, two surface conditions are studied for each material: ground and chemically passivated. The corrosion behavior is evaluated by cyclic polarization tests in 0.6 M NaCl and the morphology of pitting corrosion is characterized by optical microscopy. According to the results, the applied surface treatment causes an improvement on the pitting corrosion resistance of both stainless steels, and the greatest increase on pitting potential is obtained to the 17–4 PH stainless steel.