STRESS CORROSION CRACKING OF 321 STAINLESS STEEL SINGLE CRYSTAL UNDER MODE Ⅱ LOADING
QIAO Lijie;SHE Dongling; LIU Hui; CHU Wuyang; XIAO Jimei(University of Science and Technology Beijing)
Cite this article:
QIAO Lijie;SHE Dongling; LIU Hui; CHU Wuyang; XIAO Jimei(University of Science and Technology Beijing). STRESS CORROSION CRACKING OF 321 STAINLESS STEEL SINGLE CRYSTAL UNDER MODE Ⅱ LOADING. Acta Metall Sin, 1994, 30(2): 79-84.
Abstract SCC of 321 stainless steel(SS) single crystal was studied under mode II loading in a 42% boiling MgCl2 solution. The results shown that SCC initiated at the maximum normal stress site, while no SCC occurred at the maximum shear stress site. Although there were slip lines around the maximum normal site, most of SCC did not occur along the slip lines. Some micro-cracks could be observed on the slip lines using scanning electron microscope , but cracking direction was inclined about 20 degrees to the slip line and these microcracks did not propagate. The slip lines could appear owing to heat activation when a polished constant displacement specimen was heated at 150℃ for 2 h. The slip lines appeared during heating were polished before SCC experiment, SCC still initiated at the maximum site while no slip step emergence on the specimens. Those results are conflict with the″slip－dissolution ″ model of SCC. The SCC mechanism of austenitic stainless steel may be relative with the stress concentration due to dislocation pile－up, but not with slip steps. The normal stress plays an important part in the SCC.QIAO Lijie, associate professor,(Department of Materials Physics, University of Science and Technology Beijing, Beijing 100083)
