| Abstract: | The influence of the Titanium content on the active corrosion of ferritic Cr steels and austenitic Cr-Ni steels in sulphuric acids Non-stabilized and Ti-stabilized steels of types X8Cr17, X8Crti17, X5CrNi189, X10CrNiTi189 and X5CrNiMoTi25 25 are compared with each other in respect of their behaviour in the potential range of active corrosion in sulphuric acid. With ferritic 17 per cent. chromium steels, no Ti influence was detected. With more highly alloyed austenitic Cr-Ni or Cr-Ni-Mo steels, the titanium had the effect of narrowing down the potential range of active corrosion and reducing the corrosion rate which facilitates the passivation capacity of the steels. These phenomena are particularly marked with the steel known as X5CrNiMoTi25 25. With this steel, the corrosion rate in the active-passive transition range with titanium contents from 0.41 to 0.66 per cent. and about 0.66 per cent. C ist increased in the sensitivized state. Within a narrow potential range of about 200 mV, intercrystalline corrosion is encountered which decreases with increasing Ti content and is completely prevented if the C content is reduced below 0.03 per cent. The potential range of the inter-crystalline corrosion is more negative than the test potential of the Strauss test normally used for testing the grain disintegration resistance. |
