Microstructural and mechanical characterization of Ti6Al4V refurbished parts obtained by laser metal deposition

This contribution is focused on the influence of build orientation on hardness of materials sintered using direct metal laser sintering (DMLS) technology. It builds on the current research works that has monitored the influence of build orientation on a fatigue life, mechanical properties, roughness after machining, etc. In the mentioned work, a slight influence of build orientation on the above properties was shown. The hardness was measured on a Ti6Al4V alloy which was made of powder by DMLS technology. The individual materials were sintered at different laser powers, then annealed to remove internal stresses. Part of the experiment examined the metallographic analysis of materials in the direction perpendicular to the sintered layers and parallel with the sintered layers. Microhardness was measured on metallographic cross-sections and the results were statistically processed. The influence of laser power on a respective material hardness was assessed by one-way analysis of variance (ANOVA), a comparison of the hardness between sintered and sintered-annealed samples, as well as the comparison of hardness in the two considered directions was performed by t-test and F-test. A statistically significant difference in the hardness of the materials prepared at different laser powers was found. The influence of heat treatment, as well as the direction of material building also showed a statistically significant difference.

Section: Research Activities Related To Dmls/slm Of Ti6al4vmentioning

confidence: 99%

Influence of Build Orientation, Heat Treatment, and Laser Power on the Hardness of Ti6Al4V Manufactured Using the DMLS Process

Guzanová

Ižaríková

Brezinová

et al. 2017

“…Supporting structures are necessary especially when downward-facing structures, large openings on vertical walls, overhanging or angled surfaces are going to be produced. If an inclination angle does not exceed the critical value (e.g., [20][21][22][23][24][25][26][27][28][29][30] • for Ti alloys), they can be considered as self-supporting without the need for a supporting structure. The support structure represents the loss of both material and energy needed to create and remove it.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Position of Materials on a Build Platform on the Hardness, Roughness, and Corrosion Resistance of Ti6Al4V Produced by DMLS Technology

Guzanová

Draganovská

Ižaríková

et al. 2019

This article is focused on the effect of position on a build platform on the hardness, roughness and corrosion rate of parts (Ti6Al4V) produced by direct metal laser sintering (DMLS) technology. During the sintering process, the test samples were located at key positions—at the corners and in the middle of the build platform. An experimental program started with a microstructure investigation in two perpendicular directions in individual positions. The selected mechanical property—hardness—was investigated on metallographic cuts in both directions and all positions, and data sets underwent a statistical analysis (analysis of variance (ANOVA), t-test, F-test). The same procedure was repeated for an assessment of position effect to surface roughness (Kruskal–Wallis test) and material corrosion resistance. On the build platform, the course of hardness, roughness, and corrosion rate values that can be expected in individual positions was mapped in detail.

“…For its development, research nowadays involves all kinds of areas, such as process optimization [5][6][7][8][9], modelling/simulation [10][11][12][13][14], and material microstructure and mechanical properties [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

The Influence of the Powder Stream on High-Deposition-Rate Laser Metal Deposition with Inconel 718

Chen

Pirch

Gasser

et al. 2017

Abstract:For the purpose of improving the productivity of laser metal deposition (LMD), the focus of current research is set on increasing the deposition rate, in order to develop high-deposition-rate LMD (HDR-LMD). The presented work studies the effects of the powder stream on HDR-LMD with Inconel 718. Experiments have been designed and conducted by using different powder feeding nozzles-a three-jet and a coaxial powder feeding nozzle-since the powder stream is mainly determined by the geometry of the powder feeding nozzle. After the deposition trials, metallographic analysis of the samples has been performed. The laser intensity distribution (LID) and the powder stream intensity distribution (PID) have been characterized, based on which the processes have been simulated. Finally, for verifying and correcting the used models for the simulation, the simulated results have been compared with the experimental results. Through the conducted work, suitable boundary conditions for simulating the process with different powder streams has been determined, and the effects of the powder stream on the process have also been determined. For a LMD process with a three-jet nozzle a substantial part of the powder particles that hit the melt pool surface are rebounded; for a LMD process with a coaxial nozzle almost all the particles are caught in the melt pool. This is due to the different particle velocities achieved with the two different nozzles. Moreover, the powder stream affects the heat exchange between the heated particles and the melt pool: a surface boundary condition applies for a powder stream with lower particle velocities, in the experiment provided by a three-jet nozzle, and a volumetric boundary condition applies for a powder stream with higher particle velocities, provided by a coaxial nozzle.