This paper deals with the selective laser melting (SLM) processing strategy for strut-lattice structure production which uses only contour lines and allows the porosity and roughness level to be managed based on combination of the input and linear energy parameters. To evaluate the influence of a laser scanning strategy on material properties and surface roughness a set of experiments was performed. The single welds test was used to find the appropriate processing parameters to achieve continuous welds with known width. Strut samples were used to find a suitable value of weld overlapping and to clarify the influence of input and linear laser energy on the strut porosity and surface roughness. The samples of inclined hollow struts were used to compare the wall thickness with single welds width; the results showed about 25% wider welds in the case of a hollow strut. Using the proposed SLM strategy it is possible to reach a significantly lower porosity and surface roughness of the struts. The best results for struts with an inclination of 35.26° were achieved with 25% track overlapping, input energy in the range from 9 J to 10.5 J and linear energy Elin from 0.25 to 0.4 J/mm; in particular, the relative density of 99.83% and the surface roughness on the side of the strut of Ra 14.6 μm in an as-built state was achieved.

No abstract

Magnesium alloys are perspective materials for use in transportation, aerospace and medical industries, mainly because of their good load-to-weight ratio, biocompatibility and biodegradability. For the effective production of magnesium components by the laser powder bed fusion (LPBF) process, the process parameters with verified mechanical properties need to be determined. In this paper, we prepared bulk samples with a high relative density of AZ91D magnesium alloy. Tensile tests were then performed on LPBF samples to evaluate the mechanical properties. Our results show that the bulk samples achieved a relative density >99%, in multiple planes over the full sample height, while the mechanical properties reached values of YS = 181 MPa, UTS = 305 MPa and A5.65 = 5.2%. The analysis by scanning electron microscope revealed fine β-Mg17Al12 particles in the microstructure, which have a positive effect on the mechanical properties. The chemical composition of magnesium alloy AZ91D changed slightly during processing by LPBF due to the evaporation of the Mg content. However, the resulting composition still corresponds to the range specified by the ASTM standard for the AZ91D alloy.

The process parameters of the Laser Metal Deposition technology in the production of simple components made of NiCuBSi type metal powder were verified in this paper. A laser head with a coaxial powder supply and argon gas was used in the production. The powder was welded to a S235J2G3 steel plate. The used parameters (heat input 0.25 kJ.mm−1) enabled the production of samples with a minimum porosity (1.2 %) and without the defects (cold joints, pores) between the weld layers.