Localized corrosion of 15-5 PH and 17-4 PH stainless steel in NaCl solution

The importance in the selection of materials in the aeronautical industry for the manufacture of an aircraft is related to the fact that the materials are present during the life cycle of the aircraft. In particular, the precipitation hardening (PH) stainless steel is used in components that require the combination of excellent mechanical properties, as well as corrosion resistance due to aircraft exposure in harsh environments. Inherently corrosion resistant steels achieve an important characteristic which is passivation by forming a protective layer of chromium oxide on the surface. This research aimed to conduct an analysis of the localized corrosion on stainless steel 15-5 PH and 17-4 PH, used on fasteners or engine components. The steels were evaluated in a 3.5 wt.% NaCl solution, using the electrochemical technique of cyclic potentiodynamic polarization curves (CPP) according to the ASTM 61-86 standard. The microstructural analysis was performed by optical microscopy (OM) and scanning electron microscopy (SEM). The results indicated that CPP curves showed a positive hysteresis, indicating pitting localized corrosion and the corrosion current density of the 15-5 PH and 17-4 PH stainless steels were 1.31 x 10(-8) and 2.70 x 10(-8) A/cm(2).