Influence of storage conditions and reconditioning of AlSi10Mg powder on the quality of parts produced by laser powder bed fusion (LPBF)

2021 ◽  
Vol 39 ◽  
pp. 101896
Author(s):  
Kirstin Riener ◽  
Steffen Oswald ◽  
Michael Winkler ◽  
Gerhard J. Leichtfried
Keyword(s):  
Storage Conditions ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed

scholarly journals Improving the quality of up-facing inclined surfaces in laser powder bed fusion of metals using a dual laser setup

Procedia CIRP ◽  
2020 ◽  
Vol 94 ◽  
pp. 266-269 ◽  
Author(s):  
Jitka Metelkova ◽  
Daniel Ordnung ◽  
Yannis Kinds ◽  
Ann Witvrouw ◽  
Brecht Van Hooreweder
Keyword(s):  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Inclined Surfaces ◽  
Dual Laser ◽  
Laser Setup

Design Rules and In-Situ Quality Monitoring of Thin-Wall Features Made Using Laser Powder Bed Fusion

2019 ◽  
Author(s):  
Aniruddha Gaikwad ◽  
Farhad Imani ◽  
Prahalad Rao ◽  
Hui Yang ◽  
Edward Reutzel
Keyword(s):  
Neural Network ◽  
Aspect Ratio ◽  
Convolutional Neural Network ◽  
Thin Wall ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Design Rules ◽  
Powder Bed

Abstract The goal of this work is to quantify the link between the design features (geometry), in-situ process sensor signatures, and build quality of parts made using laser powder bed fusion (LPBF) additive manufacturing (AM) process. This knowledge is critical for establishing design rules for AM parts, and to detecting impending build failures using in-process sensor data. As a step towards this goal, the objectives of this work are two-fold: 1) Quantify the effect of the geometry and orientation on the build quality of thin-wall features. To explain further, the geometry-related factor is the ratio of the length of a thin-wall (l) to its thickness (t) defined as the aspect ratio (length-to-thickness ratio, l/t), and the angular orientation (θ) of the part, which is defined as the angle of the part in the X-Y plane relative to the re-coater blade of the LPBF machine. 2) Assess the thin-wall build quality by analyzing images of the part obtained at each layer from an in-situ optical camera using a convolutional neural network. To realize these objectives, we designed a test part with a set of thin-wall features (fins) with varying aspect ratio from Titanium alloy (Ti-6Al-4V) material — the aspect ratio l/t of the thin-walls ranges from 36 to 183 (11 mm long (constant), and 0.06 mm to 0.3 mm in thickness). These thin-wall test parts were built under three angular orientations of 0°, 60°, and 90°. Further, the parts were examined offline using X-ray computed tomography (XCT). Through the offline XCT data, the build quality of the thin-wall features in terms of their geometric integrity is quantified as a function of the aspect ratio and orientation angle, which suggests a set of design guidelines for building thin-wall structures with LPBF. To monitor the quality of the thin-wall, in-process images of the top surface of the powder bed were acquired at each layer during the build process. The optical images are correlated with the post build quantitative measurements of the thin-wall through a deep learning convolutional neural network (CNN). The statistical correlation (Pearson coefficient, ρ) between the offline XCT measured thin-wall quality, and CNN predicted measurement ranges from 80% to 98%. Consequently, the impending poor quality of a thin-wall is captured from in-situ process data.

scholarly journals The Size Effect on Forming Quality of Ti–6Al–4V Solid Struts Fabricated via Laser Powder Bed Fusion

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 416 ◽  
Author(s):  
Huixin Liang ◽  
Deqiao Xie ◽  
Yuyi Mao ◽  
Jianping Shi ◽  
Changjiang Wang ◽  
...  
Keyword(s):  
Size Effect ◽  
Geometric Characteristic ◽  
Characteristic Size ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Micro Computed Tomography ◽  
Forming Quality ◽  
Powder Bed ◽  
Scan Speed

Laser powder bed fusion (LPBF) is useful for manufacturing complex structures; however, factors affecting the forming quality have not been clearly researched. This study aimed to clarify the influence of geometric characteristic size on the forming quality of solid struts. Ti–6Al–4V struts with a square section on the side length (0.4 to 1.4 mm) were fabricated with different scan speeds. Micro-computed tomography was used to detect the struts’ profile error and defect distribution. Scanning electron microscopy and light microscopy were used to characterize the samples’ microstructure. Nanoindentation tests were conducted to evaluate the mechanical properties. The experimental results illustrated that geometric characteristic size influenced the struts’ physical characteristics by affecting the cooling condition. This size effect became obvious when the geometric characteristic size and the scan speed were both relatively small. The solid struts with smaller geometric characteristic size had more obvious size error. When the geometric characteristic size was smaller than 1 mm, the nanohardness and elastic modulus increased with the increase in scan speed, and decreased with the decline of the geometric characteristic size. Therefore, a relatively high scan speed should be selected for LPBF—the manufacturing of a porous structure, whose struts have small geometric characteristic size.

scholarly journals On the quality of unsupported overhangs produced by laser powder bed fusion

2019 ◽  
Vol 14 (2) ◽  
pp. 198
Author(s):  
Gabriele Piscopo ◽  
Alessandro Salmi ◽  
Eleonora Atzeni
Keyword(s):  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed

scholarly journals A Review of Model Inaccuracy and Parameter Uncertainty in Laser Powder Bed Fusion Models and Simulations

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Tesfaye Moges ◽  
Gaurav Ameta ◽  
Paul Witherell
Keyword(s):  
Parameter Uncertainty ◽  
Computational Models ◽  
Predictive Accuracy ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Uncertainty Sources ◽  
Model Fidelity ◽  
Physical Phenomena

This paper presents a comprehensive review on the sources of model inaccuracy and parameter uncertainty in metal laser powder bed fusion (L-PBF) process. Metal additive manufacturing (AM) involves multiple physical phenomena and parameters that potentially affect the quality of the final part. To capture the dynamics and complexity of heat and phase transformations that exist in the metal L-PBF process, computational models and simulations ranging from low to high fidelity have been developed. Since it is difficult to incorporate all the physical phenomena encountered in the L-PBF process, computational models rely on assumptions that may neglect or simplify some physics of the process. Modeling assumptions and uncertainty play significant role in the predictive accuracy of such L-PBF models. In this study, sources of modeling inaccuracy at different stages of the process from powder bed formation to melting and solidification are reviewed. The sources of parameter uncertainty related to material properties and process parameters are also reviewed. The aim of this review is to support the development of an approach to quantify these sources of uncertainty in L-PBF models in the future. The quantification of uncertainty sources is necessary for understanding the tradeoffs in model fidelity and guiding the selection of a model suitable for its intended purpose.

scholarly journals Finite Element Modeling of Melt Pool Dynamics in Laser Powder Bed Fusion of 316L Stainless Steel

2021 ◽  
Author(s):  
Juan Trejos-Taborda ◽  
Luis Reyes-Osorio ◽  
Carlos Garza ◽  
Patricia del Carmen Zambrano-Robledo ◽  
Omar Eduardo Lopez-Botello
Keyword(s):  
Numerical Model ◽  
Relative Error ◽  
Laser Scanning ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Melt Pool ◽  
History Of ◽  
Dynamics Stability

Abstract In Laser Powder Bed Fusion (LPBF), melt pool dynamics stability determines the overall quality of a manufactured component. In this work, a numerical model of the LPBF process was developed in order to study and fully understand the behavior of the melt pool dynamics. The numerical model takes into account most of the manufacturing parameters, thermophysical properties, an enhanced thermal conductivity approach and a volumetric heat source in order to precisely mimic LPBF. This research assumes that the energy emitted by the laser interacts with the metal powder with an absorptivity gradient through the layer thickness in order to calculate the thermal history of the process and the evolution of the melt pool dimensions. The obtained results determined that melt pool dimensions follow a thermal pattern, which is caused by the laser scanning strategy of the LPBF process. A new effective width criterion was proposed in the present research in order to accurately relate both calculated and measured dimensions of the melt pool, reducing the relative error of the model and obtaining data scattering with a standard deviation of ±7.21 µm and a relative error of 2.92%.

scholarly journals Hybrid dual laser processing for improved quality of inclined up-facing surfaces in laser powder bed fusion of metals

2021 ◽  
pp. 117263
Author(s):  
Jitka Metelkova ◽  
Lars Vanmunster ◽  
Han Haitjema ◽  
Daniel Ordnung ◽  
Jean-Pierre Kruth ◽  
...  
Keyword(s):  
Laser Processing ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Dual Laser
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