THE CORROSION BEHAVIOUR OF FERRITIC STAINLESS STEELS IN ALKALINE SOLUTIONS KOROZIJSKO VEDENJE FERITNIH NERJAVNIH JEKEL V ALKALNIH RAZTOPINAH

The corrosion resistances of X6Cr17 and X2CrTi17 ferritic stainless steels and cold-rolled, low-carbon steel, as well as circular and transversal welds of X6Cr17 ferritic stainless steel, were investigated in a non-phosphate detergent with a solution pH of 10.5 and at a temperature of 60°C. The second investigated solution contained the non-phosphate detergent and sodium perborate tetrahydrate at pH 11 and was at a temperature of 90°C. The potentiodynamic measurements showed that the corrosion resistance decreased from X2CrTi17 and X6Cr17 to the welded specimens and the cold-rolled, low-carbon steel in non-phosphate detergent at the lower temperature. At the elevated temperature and with the addition of sodium perborate tetrahydrate the corrosion stability of all the investigated materials decreased significantly. Keywords: ferritic stainless steel, potentiodynamic, alkaline solution, corrosion Preu~evali smo korozijsko odpornost vzorcev X6Cr17, X2CrTi17 feritnih nerjavnih jekel, hladno valjanega malooglji~nega jekla in kro`nega ter pre~nega zvara X6Cr17 feritnega nerjavnega jekla v raztopini nefosfatnega detergenta pri pH 10,5 in temperaturi 60°C. Druga preiskovana raztopina je vsebovala nefosfatni detergent in natrijev perborat tetrahidrat pri pH 11 in temperaturi 90°C. Rezultati potenciodinamskih meritev so pokazali, da sta korozijsko najbolj obstojna materiala X2CrTi17 in X6Cr17, manj pa obe vrsti zvarov in hladno valjano malooglji~no jeklo. Pri povi{ani temperaturi in z dodatkom natrijevega perborata tetrahidrata se je korozijska odpornost vseh petih vzorcev izrazito zmanj{ala