Scanning-3DXRD measurement of crack tip orientation-strain states to elucidate ductile fracture mechanisms in 3D printed steels

The proposed research aims to characterize the process of plastic deformation and crack tip blunting in polycrystalline alloys made by laser-based additive manufacturing (LAM) using a combination of 3D imaging techniques. Fracture toughness in LAM alloys can be as much as 70% lower than conventional metals, however a mechanistic basis for these behaviors remains unclear. Both LAM and wrought stainless steel 316L (SS316L) polycrystals will be studied by in-situ scanning X-ray diffraction (s3DXRD) and phase contrast tomography (PCT) using the nanoscope station at ID11. The experimental data will give access to the temporal and spatial evolution of crack tip geometry and orientation-strain states to assess the influence of local grain morphology on plastic deformation and crack tip blunting throughout the 3D microstructure during in-situ crack growth experiments of notched samples.