| Abstrakt: |
The influence of SLM process parameters (laser power, scan spacing, scan strategy, scan speed, powder flow rate and layer thickness) and heat treatment on the microstructure and mechanical properties was evaluated in order to ensure optimal printing conditions. An AconityMINI (Aconity3D, Germany) LPBF system, with the single mode infrared fibre laser (400 W), was employed to produce cylindical samples with a dimension of Φ 7.5 mm and height 45 mm. Laser power of 400 with a scan speed of 800 mm/s and 900 mm/s were used to manufacture Ti6Al4V samples. The powder grain size was 45-105 μm (AP&C from Canada). The optimal process parameters were selected. Samples slice thickness of 60 |am and hatch spacing of 60 μm were performed. The volume energy density of 100 J/mm³ or more is necessary in order to achieve higher density and eliminate macro- and micro-defects. After the inspection, the samples were removed from the base, heat treated (annealing at 800°C, 2 hours and cooling in the furnace) and samples were prepared for mechanical tests. Tensile tests were performed according to the SIST EN ISO 6892-1 A224 standard. The following equipment and parameters were used: INSTRON 1255 test machine, samples type B 4x20 mm, extensiometer LMP-AE-17 (20 mm), testing speed in area 1 (elastic area): 0.00025 /s, testing speed in area 2 (area of plastic deformation): 0.0067 /s. The fracture surfaces of the tensile samples were examined with a Zeiss Crossbeam 550 electron microscope. The strength of samples produced with larger grain sizes is high and comparable to samples produced with finer powder. The elongation of samples is lower compared to samples with finer powder. The main reason for low elongation is line porosity. [ABSTRACT FROM AUTHOR] |
