ICAMS / Interdisciplinary Centre for Advanced Materials Simulation


Texture evolution during uniaxial tensile test of additively manufactured 316L stainless steel

Date: 18.09.2018
Time: 14:00
Place: 6th International Symposium on Computational Mechanics of Polycrystals, Düsseldorf, Germany

Abhishek Biswas
Mahesh Ramaswamy Guru Prasad
Napat Vajragupta
Hamad Hassan
Florian Brenne
Alexander Hartmaier

Additive manufacturing (AM) has recently come into focus for manufacturing of complex metallic structures. Selective laser melting (SLM) is an AM technique employing metal powders as basis. The resultant material can show highly textured, columnar polycrystalline microstructure as well as equiaxed grains. In case of columnar grain structure, the tensile test results of materials reveal anisotropic behavior. In light of this dependence of material behavior on geometry and texture, it is vital to produce a synthetic microstructure, which closely represents the morphology and texture of the real microstructure. This work aims at studying the evolution of texture during the uniaxial tensile test of additively manufactured 316L stainless steel. The morphology of the polycrystalline microstructure is approximated by statistical data obtained from the electron back scatter experiments (EBSD). The extracted orientation distribution from EBSD characterization consists of large number of orientations, which have to be systematically reduced to closely represent the real texture. The hybrid integer approximation[2] method has been used in this regard. Furthermore, during the deformation of polycrystals, pronounced strain gradients may occur at grain boundaries between grains, whose misorientations lead to a large mismatch in their deformation behavior. Hence, to closely represent the real microstructure not only the orientation distribution, but also the misorientation distribution has been included into the synthetic microstructure. The material behavior is defined by the non local crystal plasticity model[2]. Finally, numerical simulations of uniaxial tensile testing are performed and the rotations inside the grains occurring due to the plastic deformation is stored in form of a set of Euler angles, for every time step of simulation. These set of Euler angles are utilized to estimate the orientation distribution function at each time step, which can be used to study the evolution in texture as loading progress. In the final step experimental techniques such as X-ray diffraction (XRD), texture of material at different elongation step is characterized and compared with simulation results for verification.

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