Porosity testing methods for the quality assessment of selective laser melted parts

Wits, Wessel W.; Carmignato, Simone; Zanini, Filippo; Vaneker, Thomas H.J.

doi:10.1016/j.cirp.2016.04.054

Cited by 150 publications

(69 citation statements)

References 16 publications

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“…UIT can introduce the compressive stress into the layer, and hence reduce the tensile stress. Figure 4a shows that there are many large and irregular incomplete fusion defects in the SLM sample, due to the inappropriate hatch spacing [16] (used on purpose to generate defects). However, since UIT is applied after depositing every two layers, some small defects are basically eliminated.…”

Section: Resultsmentioning

confidence: 99%

Residual Stress, Defects and Grain Morphology of Ti-6Al-4V Alloy Produced by Ultrasonic Impact Treatment Assisted Selective Laser Melting

et al. 2016

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For large-scale selective laser melting (SLM) additive manufacturing technology, three main problems severely restrict its development and application, namely the residual stress, defects, and columnar grains with anisotropy. To overcome these problems, a new method is proposed by combining SLM with ultrasonic impact treatment (UIT) technique. This study explores the feasibility of UIT assisted SLM, as well as the effect of UIT on the residual stress, defects and β grains of Ti-6Al-4V alloy sample. The results indicate that after the application of UIT during SLM, residual stress can be largely reduced and defects can be hammered flat and even eliminated. Meanwhile, the epitaxial growth of columnar grains is prevented, and fine equiaxed grains are formed due to plastic deformation and recrystallization.

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Section: Resultsmentioning

confidence: 99%

Residual Stress, Defects and Grain Morphology of Ti-6Al-4V Alloy Produced by Ultrasonic Impact Treatment Assisted Selective Laser Melting

et al. 2016

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“…Various non‐destructive testing (NDT) methods, such as Archimedes method, gas pycnometry, and X‐ray computed tomography (CT), have been utilized to characterize defects. Archimedes method and gas pycnometry are not capable of quantitatively providing information on the size, location, or distribution of the defects . On the other hand, the volume, location, shape, and distribution of the defects in 3D space can be obtained via X‐ray CT.…”

Section: Effect Of Defectsmentioning

confidence: 99%

“…Archimedes method and gas pycnometry are not capable of quantitatively providing information on the size, location, or distribution of the defects. 20,21 On the other hand, the volume, location, shape, and distribution of the defects in 3D space can be obtained via X-ray CT. However, the CT process is relatively expensive and defects due to LOF containing unmelted powder particles may not be fully detectable by CT. A simple destructive method, such as microscopic cross-section analysis performed on AM parts using optical microscopy or scanning electron microscopy (SEM), may be beneficial in terms of achieving high resolution and accuracy in measuring size, shape, and location of the microscopic defects.…”

Section: Introductionmentioning

confidence: 99%

Fatigue behaviour of additive manufactured materials: An overview of some recent experimental studies on Ti‐6Al‐4V considering various processing and loading direction effects

Fatemi

Molaei

Simsiriwong

et al. 2019

Fatigue Fract Eng Mat Struct

151

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Although additive manufacturing (AM) has gained significant attention due to the advantages it offers and is currently a focus of much research, design of critical load carrying components utilizing such processes is still at its infancy. This is due to the fact that most of the load carrying components made by AM processes are subjected to cyclic loads, and fatigue behaviour of AM metals is far less understood as compared with those made by conventional methods, such as wrought and cast metals. To better understand the fatigue behaviour of AM metals, a wide range of issues that affect the behaviour in a synergistic manner must be considered. These include the effects of defects, residual stresses, surface finish, geometry and size, layer orientation, and heat treatment. Additionally, due to the multiaxial nature of the loading and/or complex geometries typically manufactured by AM processes, the stress state is often multiaxial including both normal and shear stresses. In this paper, the aforementioned effects influencing the fatigue resistance of AM parts, including torsion and multiaxial fatigue behaviour, are briefly discussed using some recently generated experimental data on Ti‐6Al‐4V by the authors.

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“…15 A possible nondestructive test method to identify and characterize the process-induced porosity is the use of Xray computed tomography (CT). The method is widely used for different AM materials such as aluminum [16][17][18] and titanium alloys 19,20 for density measurements and characterization of pores and cracks. However, steels are challenging for X-ray applications due to their high density, high absorption coefficient, and the effect of beam hardening, causing artifacts and noise in the CT data.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the anisotropic cyclic damage behavior of selective laser melted AISI 316L stainless steel

Stern

Kleinhorst

Tenkamp

et al. 2019

Fatigue Fract Eng Mat Struct

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The additive manufacturing technique selective laser melting (SLM) is the most common process for metallic powders. The layer‐by‐layer process allows construction of components with high complex designs compared with conventional process routes. However, the orientation of parts related to the build platform and later to different loading conditions should be taken into account as the process‐induced microstructure and defects creating anisotropic mechanical behavior. To evaluate this influence of the building orientation as well as the process‐induced defects, different fatigue tests were performed on the SLM‐processed austenitic steel AISI 316 L (X2CrNiMo17‐12‐2). The distribution of the process‐induced porosity and, thus, the fatigue behavior is strongly related to the building direction, leading to a reduction of fatigue life for the tested 90° specimens of more than 90%.

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Porosity testing methods for the quality assessment of selective laser melted parts

Cited by 150 publications

References 16 publications

Residual Stress, Defects and Grain Morphology of Ti-6Al-4V Alloy Produced by Ultrasonic Impact Treatment Assisted Selective Laser Melting

Residual Stress, Defects and Grain Morphology of Ti-6Al-4V Alloy Produced by Ultrasonic Impact Treatment Assisted Selective Laser Melting

Fatigue behaviour of additive manufactured materials: An overview of some recent experimental studies on Ti‐6Al‐4V considering various processing and loading direction effects

Investigation of the anisotropic cyclic damage behavior of selective laser melted AISI 316L stainless steel

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