MORPHOLOGY OF EXTRUSIONS INDUCED BY FATIGUE IN 316L STAINLESS STEEL: A LOCAL ELECTRON BACK SCATTERING DIFFRACTION/ATOMIC FORCE MICROSCOPY ANALYSIS

摘要

The morphology of extrusions induced by low cycle fatigue in a 316L stainless steel has been studied in relation to local crystallographic configuration. For that, electron back scattering diffraction (EBSD) and atomic force microscopy (AFM) were combined in the same areas. EBSD allowed to identify activated slip planes and to calculate their theoretical inclination. AFM were used to measure the height of extrusions at a nanometer scale. A special attention was paid to the first stage of extrusion emergence before crack initiation. Results concerned fatigue tests performed in vacuum in order to study surface slip features independently of any environmental induced effects. It has been shown that extrusions are characterized by a flat part on their bottom that corresponds to {111} slip planes and an irregular profile at the top. There is a good correspondence between the inclination of the flat part calculated by EBSD and measured by AFM.