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The 3D printing process is a recent technique, which allows one to produce parts of complex geometry. The influence of printing parameters on the mechanical and structural properties of many materials has been extensively studied. However, despite the considerable amount of research, the task of comparing the results of different scientific groups is complicated. Each research group performs the investigation with different printing conditions. A lot of works contain not full information about the printing process parameters which were applied. This paper presents the results on the mechanical and structural properties of 316L stainless steel according to variable printing parameters, such as laser density energy, scan strategy, and build direction at other fixed conditions. The results reveal a parabolic dependency between the mechanical properties and the laser density energy. The laser density energy of 161 J/mm 3 leads to the best mechanical characteristics (yield strength of 530 MPa, ultimate strength of 580 MPa, and ductility of 63.2%). Scan strategy does not influence the mechanical properties of the samples printed in the vertical direction. At the same time, the strong scan strategy effect is observed for the samples printed in horizontal direction. The difference in the ultimate strength between the vertically and horizontally printed samples reaches up to 70 MPa.

Unique functional properties such as the low stiffness, superelasticity, and biocompatibility of nickel–titanium shape-memory alloys provide many applications for such materials. Selective laser melting of NiTi enables low-cost customization of devices and the manufacturing of highly complex geometries without subsequent machining. However, the technology requires optimization of process parameters in order to guarantee high mass density and to avoid deterioration of functional properties. In this work, the melt pool geometry, surface morphology, formation mode, and thermal behavior were studied. Multiple combinations of laser power and scanning speed were used for single-track preparation from pre-alloyed NiTi powder on a nitinol substrate. The experimental results show the influence of laser power and scanning speed on the depth, width, and depth-to-width aspect ratio. Additionally, a transient 3D FE model was employed to predict thermal behavior in the melt pool for different regimes. In this paper, the coefficients for a volumetric double-ellipsoid heat source were calibrated with bound optimization by a quadratic approximation algorithm, the design of experiments technique, and experimentally obtained data. The results of the simulation reveal the necessary conditions of transition from conduction to keyhole mode welding. Finally, by combining experimental and FE modeling results, the optimal SLM process parameters were evaluated as P = 77 W, V = 400 mm/s, h = 70 μm, and t = 50 μm, without printing of 3D samples.