Modeling of the pores formation process and experimental in situ verification of its relationship with the anisotropy of SLM products

The purpose of research. The hypothesis that the anisotropy of the properties of selective laser fusion powder products is solely related to their porosity is controversial. The authors substantiate the ideas about the significant effect on the anisotropy of the properties of SLM products, their heterogeneity and the unevenness of the plastic flow of local plasticity zones formed at the pores during loading. The purpose of this work is to model pore formation and mathematically analyze the effect of plasticity zones on anisotropy, heterogeneity of mechanical properties and plastic flow of SLM technology products on the micro and macroscale.
Methods. To achieve this goal, simulation and computational modeling of the pore formation process in samples of powder alloys 316L and Inconel 718 made by layered laser fusion, as well as their uniaxial tensile tests with microstructure analysis (optical and SEM) and X-ray computed tomography were used.
Results. The role of pores as stress concentrators and foci of local plasticity forming autowaves of plastic deformation is substantiated. This fact was confirmed by a mathematical analysis of the distribution of local deformations over the length of samples and test time using the decomposition of their arrays into a Fourier series and their subsequent Fourier interpolation.
Conclusion. Equations describing the effect of stress and strain intensity on the development of the indicator of heterogeneity of mechanical properties and the unevenness of the plastic flow of the studied alloys at the micro and macroscale are obtained. It is proposed to use them to automate the analysis of the evolution of anisotropy and heterogeneity of mechanical properties in SLM products.

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