The Application of Powder Rheology in Additive Manufacturing

Powder Recycling Effects on the Tensile and Fatigue Behavior of Additively Manufactured Ti-6Al-4V Parts

“…In addition, apparent density was found to be lower for the new powder compared to the used powder (2% difference), which can be attributed to the relatively higher interparticle frictions and cohesion in the new powder, as also reported by Seyda et al 9 As a result of wider PSD, larger BFE and smaller apparent density of the new powder, there might be a more uneven layer distribution of the powder on the build plate that can potentially cause more defects in the final part. 1,2,11,15,40 As shown earlier, changes in mechanical properties (e.g., yield strength) of specimens fabricated from new and used powder were negligible. These results differ from other studies such as Tang et al, 7 where the yield and ultimate tensile strength increased with powder recycling iterations due to higher oxygen content in Ti-6Al-4V parts produced by EBM.…”

“…2 In addition, it has been found that different mixtures of new and used powder (e.g., 25:75, 50:50, and 75:25) can affect the basic flowability energy (BFE), defined as the amount of energy required to move the blade within the powder, and that flowability does not change linearly with the amount of new powder in the mixture. 15 Some recent studies have investigated the effects of recycling on the powder characteristics and, subsequently, the mechanical behavior of AM parts for different material systems such as stainless steels, 16,17 Inconel 718 18,19 and Ti-6Al-4V. [7][8][9][19][20][21][22][23] Jacob et al 16 fabricated 11 similar L-PBF builds using new and used nitrogen atomized 17-4 PH stainless steel powder, and they evaluated hardness, tensile behavior, and surface roughness of the parts as the powder was reused.…”

Comparison of three rotational shear cell testers: Powder flowability and bulk density

“…Many studies have been conducted involving the shear cell [29,30]. Much of this work has been focused on determining whether shear cell measurements are applicable to specific situations [31][32][33][34][35][36]. In addition, changes in various aspects of the procedure (ones not dictated by the standards) have been studied [37][38][39].…”

Powders for powder bed fusion: a review

“…The need in industry for fast, reproducible, and close-toprocess powder characterization techniques is steeply rising with the increasing application of powder bed fusion (PBF) technologies. It is a generally accepted fact that the quality of powders used in PBF is key for the process performance and final part quality [1][2][3][4][5][6][7][8]. Hence, the comprehensive understanding of powder influence in the PBF process is a basic requirement to pave the way for regular fabrication of components on an industrial scale with precisely predefined and reproducible properties.…”