For the shroud rings used for 200MW generators the study has been conducted on strength by limited elements and on stress corrosion mechnism of the steels of which the rings are made.Furthermore

for the shroud ring steels 18Mn4Cr and 18Mn18Cr have been made analysis on their chemical composition

mechanical properties under ambient temperature

failure toughness under the corrosive atmosphere

four point bend stress corrosion crack

stress corrosion test under low strain change velocity

and tests for determining the fatigue crack propagation velocity and low-cycle fatigue test for 50Mn 18Cr4WN steel as Well.