Deformation and control method of thin-walled part during laser powder bed fusion of Ti–6Al–4V alloy

2020 ◽  
Vol 110 (11-12) ◽  
pp. 3467-3478
Author(s):  
Changpeng Chen ◽  
Zhongxu Xiao ◽  
Haihong Zhu ◽  
Xiaoyan Zeng
Keyword(s):  
Control Method ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Thin Walled ◽  
And Control

On the manufacturability of Inconel 718 thin-walled honeycomb structures by laser powder bed fusion

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
José M. Zea Pérez ◽  
Jorge Corona-Castuera ◽  
Carlos Poblano-Salas ◽  
John Henao ◽  
Arturo Hernández Hernández
Keyword(s):  
Mechanical Properties ◽  
Inconel 718 ◽  
Dimensional Accuracy ◽  
Honeycomb Lattice ◽  
Lattice Structures ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Content Type ◽  
Powder Bed ◽  
Thin Walled

Purpose The purpose of this paper is to study the effects of printing strategies and processing parameters on wall thickness, microhardness and compression strength of Inconel 718 superalloy thin-walled honeycomb lattice structures manufactured by laser powder bed fusion (L-PBF). Design/methodology/approach Two printing contour strategies were applied for producing thin-walled honeycomb lattice structures in which the laser power, contour path, scanning speed and beam offset were systematically modified. The specimens were analyzed by optical microscopy for dimensional accuracy. Vickers hardness and quasi-static uniaxial compression tests were performed on the specimens with the least difference between the design wall thickness and the as built one to evaluate their mechanical properties and compare them with the counterparts obtained by using standard print strategies. Findings The contour printing strategies and process parameters have a significant influence on reducing the fabrication time of thin-walled honeycomb lattice structures (up to 50%) and can lead to improve the manufacturability and dimensional accuracy. Also, an increase in the young modulus up to 0.8 times and improvement in the energy absorption up to 48% with respect to those produced by following a standard strategy was observed. Originality/value This study showed that printing contour strategies can be used for faster fabrication of thin-walled lattice honeycomb structures with similar mechanical properties than those obtained by using a default printing strategy.

scholarly journals The Dimensional Accuracy of Thin-Walled Parts Manufactured by Laser-Powder Bed Fusion Process

2020 ◽  
Vol 4 (3) ◽  
pp. 91
Author(s):  
Josef Tomas ◽  
Leonhard Hitzler ◽  
Marco Köller ◽  
Jonas von Kobylinski ◽  
Michael Sedlmajer ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Dimensional Accuracy ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Cooling Channels ◽  
Thin Walled ◽  
Scanning Strategies ◽  
Different Diameters ◽  
Functional Components

Laser-Powder Bed Fusion brings new possibilities for the design of parts, e.g., cutter shafts with integrated cooling channels close to the contour. However, there are new challenges to dimensional accuracy in the production of thin-walled components, e.g., heat exchangers. High degrees of dimensional accuracy are necessary for the production of functional components. The aim is to already achieve these during the process, to reduce post-processing costs and time. In this work, thin-walled ring specimens of H13 tool steel are produced and used for the analysis of dimensional accuracy and residual stresses. Two different scanning strategies were evaluated. One is a stripe scan strategy, which was automatically generated and provided by the machine manufacturer, and a (manually designed) sectional scan strategy. The ring segment strategy is designed by manually segmenting the geometry, which results in a longer preparation time. The samples were printed in different diameters and analyzed with respect to the degree of accuracy and residual stresses. The dimensional accuracy of ring specimens could be improved by up to 81% with the introduced sectional strategy compared to the standard approach.

scholarly journals Achieving Triply Periodic Minimal Surface Thin-Walled Structures by Micro Laser Powder Bed Fusion Process

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 705
Author(s):  
Shuo Qu ◽  
Junhao Ding ◽  
Xu Song
Keyword(s):  
Minimal Surface ◽  
Lattice Structures ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Thin Walled Structures ◽  
Periodic Minimal Surface ◽  
Triply Periodic ◽  
Triply Periodic Minimal Surface ◽  
Thin Walled

Recently, triply periodic minimal surface (TPMS) lattice structures have been increasingly employed in many applications, such as lightweighting and heat transfer, and they are enabled by the maturation of additive manufacturing technology, i.e., laser powder bed fusion (LPBF). When the shell-based TPMS structure’s thickness decreases, higher porosity and a larger surface-to-volume ratio can be achieved, which results in an improvement in the properties of the lattice structures. Micro LPBF, which combines finer laser beam, smaller powder, and thinner powder layer, is employed in this work to fabricate the thin-walled structures (TWS) of TPMS lattice by stainless steel 316 L (SS316L). Utilizing this system, the optimal parameters for printing TPMS-TWS are explored in terms of densification, smoothness, limitation of thickness, and dimensional accuracy. Cube samples with 99.7% relative density and a roughness value of 2.1 μm are printed by using the energy density of 100 J/mm3. Moreover, a thin (100 μm thickness) wall structure can be fabricated through optimizing parameters. Finally, the TWS samples with various TPMS structures are manufactured to compare their heat dissipation capability. As a result, TWS sample of TPMS lattice exhibits a larger temperature gradient in the vertical direction compared to the benchmark sample. The steady-state temperature of the sample base presents a 7 K decrease via introducing TWS.

Hybrid Surface Characterisation of Intra Thin-Walled Ti6Al4V Surfaces Produced by Laser Powder Bed Fusion Technology

2022 ◽  
Author(s):  
Anand Kumar S ◽  
Ajay Kushwaha ◽  
Nagesha B K ◽  
Sanjay Barad
Keyword(s):  
Fractal Dimension ◽  
Powder Bed Fusion ◽  
Fusion Technology ◽  
Laser Powder Bed Fusion ◽  
Surface Characterisation ◽  
Powder Bed ◽  
Powder Particles ◽  
Thin Walled ◽  
Imagej Software ◽  
Areal Surface

Abstract The proposed work investigates the hybrid surface characterisation of intra thin-walled Ti6Al4V surfaces fabricated using laser powder bed fusion technology. The thin-walled samples were characterised using scanning electron microscopy and Opto-digital microscopy techniques. The fractal dimensional analysis was performed using ImageJ software integrated with an open-source MultiFrac plug-in. The surface microscopy analysis revealed satellites powder particles, partially melted powder particles, spherical balling, and pores on the thin-walled surface. The fractal dimension establishes a correlation between the surface roughness values. The surface areal surface parameters analysis suggested variation along the build direction of thin-walled Ti6Al4V sample. The development of sharp peaks and thus higher Ra, Sku and Ssk values were found along the build direction of the intra thin-walled samples. Therefore, the combination of areal surface topography analysis and fractal dimension approach can be a promising methodology towards surface characterisation of additively manufactured complex thin-walled surfaces.

scholarly journals Keyhole fluctuation and pore formation mechanisms during laser powder bed fusion additive manufacturing

2021 ◽  
Author(s):  
Yuze Huang ◽  
Tristan Fleming ◽  
Samuel Clark ◽  
Sebastian Marussi ◽  
Fezzaa Kamel ◽  
...  
Keyword(s):  
Hydrogen Diffusion ◽  
Formation Mechanisms ◽  
Powder Bed Fusion ◽  
Monitoring And Control ◽  
Laser Powder Bed Fusion ◽  
Metal Vapour ◽  
Powder Bed ◽  
X Ray Imaging ◽  
Monitoring And Control Systems ◽  
And Control

Abstract Keyhole porosity is a key concern in laser powder-bed fusion (LPBF), potentially impacting component fatigue life. However, the dynamics of keyhole porosity formation, i.e., keyhole fluctuation, collapse and bubble growth and shrinkage, remain unclear. Using synchrotron X-ray imaging we reveal keyhole and bubble behaviours, quantifying their formation mechanisms. The findings support the hypotheses that: (i) keyhole porosity can initiate not only in unstable, but also transition keyhole regimes, created by high laser power-velocity conditions, causing fast radial keyhole fluctuations (~ 10 kHz); (ii) transition regime collapse tends to occur part way up the rear-wall; and (iii) immediately after keyhole collapse, the bubble grows as pressure equilibrates then shrinks due to metal-vapour condensation. Concurrent with condensation, hydrogen diffusion into the bubble slows the shrinkage and stabilises the bubble size. The physics revealed here can guide the development of real-time monitoring and control systems for keyhole porosity.

scholarly journals Warpage Analysis and Control of Thin-Walled Structures Manufactured by Laser Powder Bed Fusion

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 686
Author(s):  
Xufei Lu ◽  
Michele Chiumenti ◽  
Miguel Cervera ◽  
Hua Tan ◽  
Xin Lin ◽  
...  
Keyword(s):  
Thermal Stresses ◽  
Design Parameters ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Original Design ◽  
Powder Bed ◽  
Finite Element Software ◽  
Thin Walled Structures ◽  
Thin Walled ◽  
Plane Displacement

Thin-walled structures are of great interest because of their use as lightweight components in aeronautical and aerospace engineering. The fabrication of these components by additive manufacturing (AM) often produces undesired warpage because of the thermal stresses induced by the manufacturing process and the components’ reduced structural stiffness. The objective of this study is to analyze the distortion of several thin-walled components fabricated by Laser Powder Bed Fusion (LPBF). Experiments are performed to investigate the sensitivity of the warpage of thin-walled structures fabricated by LPBF to different design parameters such as the wall thickness and the component height in several open and closed shapes. A 3D-scanner is used to measure the residual distortions in terms of the out-of-plane displacement. Moreover, an in-house finite element software is firstly calibrated and then used to enhance the original design in order to minimize the warpage induced by the LPBF printing process. The outcome of this shows that open geometries are more prone to warping than closed ones, as well as how vertical stiffeners can mitigate component warpage by increasing stiffness.

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