Geometric influence of the laser-based powder bed fusion process in Ti6AL4V and AlSi10Mg

Abstract

Many studies have shown that the mechanical properties and geometric accuracy of additive manufacturing parts are dependence of many factors such as laser energy density, build orientation and heat transfer histories. Among the factors, heat transfer histories are highly dependent on the geometry of a part, resulting in influencing the mechanical properties and microstructure evolution due to repeated heating and cooling process. Heat transfer histories are associated with material thermal properties which includes thermal conductivity, thermal diffusivity, specific heat capacity and temperature gradient. The objective of this paper is to understand and observe the microstructure evolution process and micro-hardness based on variation in geometrical characteristic of the laser-based powder bed fusion (L-PBF). This paper presents the effect of the geometric factors on the mechanical properties and geometric accuracy during L-PBF process, which benefit future process optimization and modelling. In this study, samples with varying wall thickness are fabricated in TI6AL4Vand AlSi10Mg alloys by L-PBF. The samples are systematically evaluated by the optical microscope and Vickers hardness tester. Microstructural characterization of these samples is further evaluated via scanning electron microscopy. The results show that there is a signification relationship between material thermal properties, microstructure evolution and mechanical properties with respect to the variation in wall thickness. These results can be used to understand the material thermal behaviour in lattice structures with a thin or small size feature and serve as a design guideline to indirectly control the microstructure of a L-PBF part.

Mechanical and microstructural characterization of titanium gr.5 parts produced by different manufacturing routes

“…Concerning the L-PBF and E-PBF processes, it is worth noting that critical aspects related to the process variables and part geometry are highlighted in the literature [ 20 – 24 ]. In particular, a few authors investigated the issues of producing thin-walled geometries through the leading PBF metal AM technologies, i.e., L-PBF and E-PBF, highlighting the effects of the fundamental process parameters such as heat source power, scanning speed, and layer thickness on the overall build quality [ 25 , 26 ]. From the results, they reported that parts with thinner walls do suffer from a worse surface quality, lower static and dynamic mechanical properties, and higher hardness.…”

Initial performance assessment of 3D printed thin walled structures for spacecraft applications

“…The difference between the designed and the fabricated wall thickness of LPBF AlSi10Mg was also recently investigated. 19 For samples between 0.3 mm and 3 mm thick, the fabricated wall thickness of AlSi10Mg is smaller than the design thickness, but no correlation with material properties was investigated apart from a study on microhardness which shows no clear trend. The tensile strength variation for sample thickness between 0.5 mm and 5 mm was studied for Ti6Al4V specimens printed through EBM and the 0.5 mm sample had a 30% lower ultimate tensile strength (UTS) compared with the 1 mm sample.…”

Comprehensive Areal Geometric Quality Characterisation of Injection Moulded Thermoplastic Gears

“…These parameters position the produced gears in the class of small module gears, which have smaller specific surface area and smaller convection and radiation heat dissipation resistance during cooling compared to typical module gears [28]. As with other manufacturing methods, where many process parameters influence the geometric quality of products [29][30][31][32], numerous factors influence the geometric deviations during plastic gear injection moulding, namely the employed processing equipment, material properties, mould structure, part shape, and injection moulding process parameters [33,34].…”