Detekce center lokalizované koroze ve vysoce legovaných materiálech

Abstract

The pitting corrosion is one of the most common reasons of stainless steels failures in solutions with chloride ions content. The diploma thesis is focused on the detection of potential sites for local types of corrosion damage initiation. In the first part the effect of temperature related to the pitting corrosion initiation. MnS inclusions has been studied using micro-electrochemical techniques with In Situ observation, which was developed in the electrochemical laboratory at Tohoku University in Japan. The second part of this thesis is focused on the influence of the addition of titanium as an alloying element on the corrosion resistance of inclusions and secondary phases in steels. The pit initiation process was investigated on AISI 304 stainless steel in 0,1 M NaCl and 0,1 M Na2SO4 solutions. The microscopic polarization measurements were performed at 25 °C and 50 °C. SEM observation was also used to understand the dissolution of MnS inclusion during the micro-chemical measurements.