Experimental Assessment and Micromechanical Modeling of Additively Manufactured Austenitic Steels under Cyclic Loading

The present work deals with the cyclic deformation behavior of additively manufactured austenitic stainless steel 316L. Since fatigue experiments are complex and time-consuming, it is important to develop accurate numerical models to predict cyclic plastic deformation and extrapolate the limited experimental results into a wider range of conditions, considering also the microstructures obtained by additive manufacturing. Herein, specimens of 316L steel are produced by powder bed fusion of metals with laser beams (PBF-LB/M) with different parameters, and cyclic strain tests are performed to assess their deformation behavior under cyclic loads at room temperature. Additionally, a micromechanical model is set up, based on representative volume elements (RVE) mimicking the microstructure of the experimentally tested material that is characterized by electron backscatter diffraction (EBSD) analysis. With the help of these RVEs, the deformation-dependent internal stresses within the microstructure can be simulated in a realistic manner. The additively manufactured specimens are produced with their loading axis either parallel or perpendicular to the building direction, and the resulting anisotropic behavior under cyclic straining is investigated. Results highlight significant effects of specimen orientation and crystallographic texture and only a minor influence of grain shape on cyclic behavior.