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    <title>Porosity</title>
    <link>https://popups.uliege.be/esaform21/index.php?id=368</link>
    <description>Index terms</description>
    <language>fr</language>
    <ttl>0</ttl>
    <item>
      <title>Effect of powder size and processing parameters on surface, density and mechanical properties of 316L elaborated by Laser Powder Bed Fusion </title>
      <link>https://popups.uliege.be/esaform21/index.php?id=1563</link>
      <description>Despite the attractive capabilities of additive manufacturing (AM) technology, the industrialization of these processes remains very low. This is attributed to the complexes physical phenomena involved in the AM process and the layered structure of the produced parts. Intense research work is still needed for the prediction and optimization of AM parts mechanical properties. In this study, the influence of particle size distribution (PSD) of stainless steel 316L (SS 316L) powders on AM parts properties was investigated. Four PSD were used to produce test parts and compare the resulting porosity, surface roughness and macro-hardness. The SS 316L specimens were fabricated by Laser Powder Bed Fusion process (LPBF) on a SLM 125HL machine using variations in laser power and scan velocity. Computed scan tomography (CT) was used to characterize the defects. Lack of fusion and keyhole defects were detected. Defects were detected even in nearly dense parts. The powder size distribution was found to affect the porosity. Results from CT tests were used to identify the minimum achievable porosities for each powder, through the appropriate selection of process parameters. The macro-hardness and surface roughness were found to vary with the powder properties.  </description>
      <pubDate>Mon, 22 Mar 2021 20:12:13 +0100</pubDate>
      <lastBuildDate>Mon, 05 Apr 2021 18:14:24 +0200</lastBuildDate>
      <guid isPermaLink="true">https://popups.uliege.be/esaform21/index.php?id=1563</guid>
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    <item>
      <title>A numerical investigation on the effects of porosity on the plastic anisotropy of additive manufactured stainless steel with various crystallographic textures </title>
      <link>https://popups.uliege.be/esaform21/index.php?id=4308</link>
      <description>For additive manufacturing materials, different process parameters might cause non-negligible microstructural defects. Due to the deficient or surplus energy input during the process, porosity would result in significantly different mechanical responses. In addition, the heterogeneity of the microstructure of additive manufactured material could increase the anisotropic behavior in both deformation and failure stages. The aim of this study is to perform a numerical investigation of the anisotropic plasticity affected by the microstructural features, in particular, texture and porosity. The coupling of the synthetic microstructure model and the crystal plasticity method is employed to consider the microstructural features and to predict the mechanical response at the macroscopic level, including both flow curve and r-value evolution. The additive manufactured 316L stainless steel is chosen as the reference steel in this study. Porosity decreases the stress of material, however, it reduces the anisotropy of material with both two types of textures. Regardless of porosity, grains with &amp;lt;111&amp;gt;//BD fiber of reference material is preferable for high strength requirement while the random orientations are favorable for homogeneous deformation in applications.  </description>
      <pubDate>Thu, 01 Apr 2021 18:02:16 +0200</pubDate>
      <lastBuildDate>Thu, 01 Apr 2021 18:02:16 +0200</lastBuildDate>
      <guid isPermaLink="true">https://popups.uliege.be/esaform21/index.php?id=4308</guid>
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    <item>
      <title>Influence of Automated Fiber Placement Parameters on Thermoplastic Composite Blanks Used on Stamp Forming Process </title>
      <link>https://popups.uliege.be/esaform21/index.php?id=366</link>
      <description>In recent years, advanced manufacturing processes have been developed to increase the speed of production in order to reduce production costs. At the scale of thermoplastic composites, the translation is the combination of advanced manufacturing processes. The focus in this study is more specifically on the coupling of automated lay-up (AFP) and stamp forming processes. To date, a consolidation process, such as press-consolidation of thermoplastic composites, obtained blanks. Several trials have begun using an automated fiber placement consolidation to reduce manufacturing time and use unidirectional material. However, the combination of AFP and stamp forming is useful if it optimizes this process without the blank’s full consolidation, which by resulting reduces the manufacturing time. This study estimates blank characteristics through thermal history imposed by a more rapid manufacturing process. A set of blanks with varying process parameters is produced to investigate the influence at the microscopic scale. The interface behaviour is observed with optical microscope and image processing. A statistical study applied to the process is carried out in order to relate the material observations to the input parameters. The results of this study are used for the study of the next process of the combination: the stamp forming.  </description>
      <pubDate>Fri, 19 Mar 2021 17:29:04 +0100</pubDate>
      <lastBuildDate>Wed, 31 Mar 2021 18:13:41 +0200</lastBuildDate>
      <guid isPermaLink="true">https://popups.uliege.be/esaform21/index.php?id=366</guid>
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