LASEK Stanislav VSB - Technical University of Ostrava

Spoluautoři MAZANCOVÁ Eva

Austenitic steels with 20-30 % Mn, and 5-10 % Al have a high level of toughness and ductility in comparison to carbon steels, used for construction of vehicles. The corrosion behavior of those steels can be negatively affected by a high manganese content, which is electrochemically non-noble element and supports certain types of localized corrosion. The paper compares the corrosion properties of the two heats of high-alloy steels developed X50MnAlNiCu27-7 in conditions after hot rolling and subsequent aging at 450 °C for 20 to 60 minutes. For comparative purposes, were used carbon steel C10 (11321) and related Mn-Al steels (X70MiAl28-9, X100MnAl28-12). The corrosion resistance of steels and heat treatment effects were compared and assessed on the basis of potentiodynamic polarization measurements in NaCl water solution, setting parameters of pitting and uniform corrosion, and determining the corrosion potential and polarization resistance in a dilute sulfuric acid solution. Comparative tests were also carried out in an environment of neutral salt spray and using the gravimetric method. Types of corrosion attack were assessed by microscopic observations. Small differences in chemical composition of melts, respectively modification of tested steels (in tenths of % wt.) practically did not show differences in their corrosion resistance. After aging, there was a slight decrease in corrosion mass losses compared to the state after hot rolling. In an acidic environment were measured significantly lower values of the polarization resistance of X50MnAlNiCu27-7 steel compared with carbon one and a slightly lower corrosion potential. It also was confirmed a negative effect of manganese and a positive of aluminum on changes of corrosion resistance of said steels.