National Research Nuclear University “MEPhI”, Moscow, Russia:

M. G. Isaenkova, Dr. Phys.-Math., Prof., e-mail: isamarg@mail.ru
Yu. A.Perlovich, Dr. Phys.-Math., Prof., Leading Scientific Researcher
A. E. Rubanov, Post-graduate, e-mail: toly.rubanov@yandex.ru
A. V. Yudin, Post-graduate

This research looked at specimens made of austenitic steel 316L by Selective Laser Melting (SLM) and designed for tensile testing in different directions (in relation to the growth direction during printing). A significant anisotropy of mechanical properties was found as a result of mechanical testing: anisotropy of the yield strength is 1.13; tensile strength — 1.10; elongation — 1.84. X-ray analysis of the texture helped understand how the crystallographic texture of the specimens changed under elongation in different directions. On the basis of strain-induced re-orientation of grains it was established that the active deformation mechanism included crystallographic slip of type {111}<110>. Depending on the orientation of stress to the internal crystallographic axes, different texture components form as a result of elongation leading to the observed anisotropy of mechanical properties. To understand how changes in the crystallographic texture influence the mechanical properties of SLM products, a model has been developed for simulating anisotropy of mechanical properties on the basis of texture analysis data using DAMASK software. The input data include grain orientation, active deformation mechanism and parameters of the phenomenological law describing hardening of slip systems. A good correlation was found between the simulation data and the results of elongation obtained for experimental specimens printed at different orientation to the growth direction, in terms of both the yield strength anisotropy and the strain-induced changes in the crystallographic texture. Thus, knowing the difference in the crystallographic texture, the results of mechanical testing of standard shape specimens can be used to define the properties of specimens of a different shape.

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