Technological implications of the Rosenthal solution for a moving point heat source in steady state on a semi-infinite solid

Impact of process parameters on the dynamic behavior of Inconel 718 fabricated via laser powder bed fusion

“…The only pores present are due to the typical gas-entrapped bubbles, which are easily recognizable by their perfectly round shape and limited size (approximately 10 μm diameter). By reducing the energy density (i.e., increasing the scan speed and the laser power), the molten pool becomes progressively more elongated and thus prone to humping instability [25,68], and the pores assume the characteristic comma shape while increasing in size [69]. These phenomena are enhanced for the lowest energy density values, as can be observed by taking the A 6 specimen as an example (Fig.…”

“…The process parameters used to print the specimens were chosen on the basis of an extension of the Rosenthal solution [40,61,62], which describes the thermal field produced in L-PBF processes. The formulation, proposed by Moda [25], was validated by Macoretta et al [44], who demonstrated that process parameters belonging to the so-defined L-PBF feasible region produce a material not affected by macroscopic metallurgical defects, and having only a slight reduction in the fatigue strength. The adopted formulation correlates the main process parameters (laser power, scan speed, hatch distance, layer thickness) and the material thermal properties through two dimensionless parameters, namely the normalized speed V * and power P * .…”

“…3 L-PBF process feasible region (white hatched region). Literature data and A 2 , A 3 , and A 5 are obtained from [25,44] The final process parameter combinations adopted in the present work are an extension of those used in [44] and were determined starting from the baseline values suggested by Renishaw and already investigated in other studies [37,43] (hereafter defined as Baseline). The remaining combinations were obtained within the feasible region by moving along a straight line having a similar margin with respect to the lack of fusion (LoF) region (hereafter defined as A i ).…”

“…Several studies [15][16][17][18][19][20][21][22] characterized the influence of the process parameters adopted during the printing process on the bulk (Young modulus, yield and tensile strength, ductility, elongation at break, porosity) and surface (fatigue strength, surface roughness) properties of the material. Considering the widely used L-PBF process, the features of the metal powder used, the parameters of the laser beam, and the heat treatments undergone by the material are the most influencing factors for the final properties of the printed component [23][24][25][26][27]. Adopting a different scanning strategy, printing direction, layer thickness, hatch distance, and energy density produces different surface textures, microstructures, and mechanical properties of the material [28][29][30][31][32][33][34][35][36][37].…”

Influence of the energy density on the Young modulus and fatigue strength of Inconel 718 produced by L-PBF

“…In this context, the present work investigates the effects of the energy density on the mechanical properties of Inconel 718. The feasible region of the process, which describes the occurrence of the principal defects characterizing the L-PBF technology (namely lack of fusion and meltpool instability [8,9]), was defined based on the analytical model proposed by Moda [10]. Several mechanical tests were used to study the Young modulus and High Cycle Fatigue (HCF) behavior of the material.…”