51 - Study of strain heterogeneity within the microstructure of an additively manufactured 316L subjected to tensile and fatigue stresses using neutron diffraction and 3DXRD.
Abstract
This study focuses on the high cycle fatigue of a 316L stainless steel additively manufactured by the LPBF process. These additively manufactured (AM) 316Ls have a fine, multi-scale microstructure in which not only the grain size and orientation of the microstructure play a role in the properties, but also the network of dislocations and the distribution of nano-oxides [1]. In this context, we studied the deformation heterogeneities between grains during a quasi-static tensile test and a fatigue test. These heterogeneities were first characterised between families of grains of different orientations, then between grains of the same orientation. Two test campaigns were carried out using large instruments. The first campaign was carried out on SALSA line in ILL. Specimens of 316L AM were subjected to in situ fatigue test using neutron diffraction to assess the deformation in the volume of the specimen. This made it possible to measure the average elastic strains in loading direction of the grains that satisfied diffraction conditions. The results make it possible to study changes in average elastic strain in the loading direction as a function of grain orientation over the course of cycles, and to highlight the anisotropy of elastic behaviour. Tensile and fatigue tests were carried out under an X-ray beam on ESRF's ID 11 beamline using the 3DXRD method [2]. The results made it possible to partially reconstruct the scanned sample and to obtain the position, orientation, relative volume and strain tensor of each reconstructed grain. During mechanical loading, the grains were tracked, making it possible to describe the evolution of the deformation tensor of each grain as a function of the macroscopic load. This revealed heterogeneous responses between grains of the same orientation. The difficulties currently encountered in the reconstruction of fine, highly deformed microstructures will be discussed.
Speaker
Lorène Héraud
Discover speaker profileI2M, Arts et Métiers Institute of Technology, Talence, France
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51 - Study of strain heterogeneity within the microstructure of an additively manufactured 316L subjected to tensile and fatigue stresses using neutron diffraction and 3DXRD.
Date/Time
21/03/2024
4:45 pm -5:05 pm
Location
Room 8