Crevices corrosion in cracks of aisi-410 used in steam turbines blades

Abstract

In this paper the effect of temperature on corrosion crack propagation produced in a stainless steel AISI-410 type was studied. The previously cracked specimens through a rotatory machine were exposed in seawater during 5 days at two temperatures (25 °C and 90 °C). The corrosion process was studied using the electrochemical noise technique (EN) and potentiodynamic polarization curves (PC). The electrochemical noise time series were used to analyze the changes in corrosion activity for AISI-410 under the mentioned experimental conditions determining the type and corrosion rate. The results show that cracks will grow when are exposed to seawater, especially at high temperatures. Physical characterization obtained from SEM reveals a great amount of corrosion products emerging from the cracks as evidence of the oxidation of the material, causing a mixed corrosion type around the cracks: uniform and pitting. From the results, it is concluded that the corrosion attack in the cracks may influence crevice corrosion, which eventually leads to stress corrosion cracking and corrosion fatigue.