Numerical and experimental investigations on manufacturability of Al–Si–10Mg thin wall structures made by LB-PBF

Abstract

Thin Wall Structures (TWS) have applications in many fields of physics and engineering. Laser-Based Powder Bed Fusion (LB-PBF) is a free-form fabrication that can easily produce the TWS in a single production step. However, due to the thin nature of this component and the interaction of thermal forces on the lateral surface, the chance of defects such as cracks and distortion is high. Therefore, this research aims to investigate the effect of power, inclination angle and the number of laser passes upon dimensional (thickness) deviation, distortion and porosity of TWS made by LB-PBF. Investigating the mentioned parameters is useful to determine the capability of LB-PBF to produce Al–Si–10Mg​ TWS as well as manufacturability of these structures. To identify the effect of inclination angle, number of laser passes and laser power on dimensional deviation, distortion and porosity a full factorial Design of Experiments (DOE) has been selected. To discuss the results statistical analyses and simulation of LB-PBF are implemented. Simulations have been carried out using computational fluid dynamic software (Flow-3D V12) and the depth and width of the meltpool are predicted. The obtained dimensions of the melt-track are then generalised based on the thickness of the TWS to confirm the accuracy of the simulation. The related rheological features of LB-PBF in the production of TWS are characterised and discussed from the results of the simulations. In this paper, the first experimentally validated simulation and experimentation of thin-walled surfaces are carried out with different inclination angles and the number of laser pass to identify the effect of these control factors, on dimensional deviation, distortion and porosity for the TWS. The meltpool phenomena for the thin wall structure are identified by fundamental rheological aspects and thermophysical properties of the material. Manufacturability and porosity are quantified for these conditions of interest, thereby providing fundamental phenomenological insight combined with practical design data for the application of TWS in LB-PBF. Results of this research show that the inclination angle and the number of laser passes in LB-PBF strongly drive the meltpool features, wall thickness, distortion and porosity. In LB-PBF of TWS, by changing the inclination angle the number of laser passes, the porosity, distortion and dimensional accuracy can be controlled.