Effect of high-temperature preheating on pure copper thick-walled samples processed by laser powder bed fusion

Malý, Martin; Koutný, Daniel; Pantělejev, Libor; Pambaguian, Laurent; Paloušek, David

doi:10.1016/j.jmapro.2021.11.035

Cited by 22 publications

(10 citation statements)

References 35 publications

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“…High temperature preheating between 300 °C and 1100 °C is commonly used in power bed fusion of metals using an electron beam (PBF-EB/M) [27], which limits the built up of residual stresses but can lead to a sintered powder cake requiring more effort during part extraction and to powder recycling losses of approximately 10 %. [28] Such sintering effects due to 400 °C preheating during PBF-LB/M of mono-material copper parts are reported in [29]. Preheating did not lead to increased amount of oxygen inside the fused part.…”

Section: Powder Selection For High Temperature Preheatingmentioning

confidence: 84%

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Fabrication of metal-ceramic substrates by laser powder bed fusion using a high-power green laser and high temperature preheating

Hecht,

Ockel,

Stoll

et al. 2024

Laser 3D Manufacturing XI

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With the increasing demand for customized products, new requirements on production processes are set. Additive manufacturing with its tool-independent character shows great potential to replace conventional manufacturing processes. This also applies to power electronic assemblies, which are currently produced with a low variety of variants in large batches. However, high-quality processing of copper is a prerequisite for power electronics applications in order to achieve low power losses and long module lifetimes. Green high-power lasers show great potential to process pure copper powder by means of powder bed fusion using a laser-based system (PBF-LB/M) and open up new opportunities in power electronics production. PBF-LB/M not only facilitates the production of mono-material components such as load connectors or heat sinks but also provides multi-material capabilities, enabling 3D metallizations on ceramic substrates for use as power electronic circuit carriers. Therefore, parametric studies on the fabrication of copper metallizations via PBF-LB/M on alumina substrates using a 1 kW green laser have been conducted and are summarized in this paper. At first, the beam-matter interaction between preheated alumina substrates and parameterized laser radiation was analyzed. Based on the results, process parameters have been defined, which were then used for the production of copper metallizations. High temperature preheating of the ceramics was applied in order avoid delamination effects due to thermomechanical stresses during solidification. In parametric studies with respect to laser power, laser velocity and hatching distance on 500 °C preheated substrates, electrical conductivities of 30 MS/m and shear strengths of 69 MPa were obtained.

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Section: Powder Selection For High Temperature Preheatingmentioning

confidence: 84%

“…As the powder losses are increasing at 600 °C, the maximum temperature is limited to 500 °C within further studies. Due to strong visible oxidations of Cu-OF powder [29] and an increased S 63 representing stronger sintering effects, Cu-ETP 45-63 is considered in following metallization studies.…”

Section: Powder Selection For High Temperature Preheatingmentioning

confidence: 99%

Fabrication of metal-ceramic substrates by laser powder bed fusion using a high-power green laser and high temperature preheating

Hecht,

Ockel,

Stoll

et al. 2024

Laser 3D Manufacturing XI

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“…% of the XRD method. The oxidation of the unfused powder does not directly affect the oxide content in the bulk material [24].…”

Section: Discussionmentioning

confidence: 95%

“…Therefore, the optimal setting must be determined for each material. Excessive preheating of the powder bed can also have a negative effect on the properties of unfused powder and limit its recycling [15,24]; thus, it needs to be checked.…”

Section: Introductionmentioning

confidence: 99%

Effect of Preheating on the Residual Stress and Material Properties of Inconel 939 Processed by Laser Powder Bed Fusion

et al. 2022

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One of the main limitations of laser powder bed fusion technology is the residual stress (RS) introduced into the material by the local heating of the laser beam. RS restricts the processability of some materials and causes shape distortions in the process. Powder bed preheating is a commonly used technique for RS mitigation. Therefore, the objective of this study was to investigate the effect of powder bed preheating in the range of room temperature to 400 °C on RS, macrostructure, microstructure, mechanical properties, and properties of the unfused powder of the nickel-based superalloy Inconel 939. The effect of base plate preheating on RS was determined by an indirect method using deformation of the bridge-shaped specimens. Inconel 939 behaved differently than titanium and aluminum alloys when preheated at high temperatures. Preheating at high temperatures resulted in higher RS, higher 0.2% proof stress and ultimate strength, lower elongation at brake, and higher material hardness. The increased RSs and the change in mechanical properties are attributed to changes in the microstructure. Preheating resulted in a larger melt pool, increased the width of columnar grains, and led to evolution of the carbide phase. The most significant microstructure change was in the increase of the size and occurrence of the carbide phase when higher preheating was applied. Furthermore, it was detected that the evolution of the carbide phase strongly corresponds to the build time when high-temperature preheating is applied. Rapid oxidation of the unfused powder was not detected by EDX or XRD analyses.

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“…Machines with larger build volumes are capable of fabricating large quantities of parts with distinct shapes at once [1]. Selective Laser Melting (SLM) is a Laser Powder Bed Fusion (LPBF) technique that selectively melts powder layers using a laser to fabricate a 3D component according to the cross-sectional profile of the Computer-Aided Drafting (CAD) model [4,5]. Aeroswift (see Figure 1) is a large volume AM machine designed and constructed in South Africa (Pretoria) in a collaboration between the Aerospace company Aerosud and the Council for Scientific and Industrial Research (CSIR).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a High-Temperature Pre-Heating System Design for a Large-Scale Additive Manufacturing System

2022

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Additive Manufacturing (AM) of titanium (Ti6Al4V) material using Selective Laser Melting (SLM) may generate significant residual stresses of a tensile nature, which can cause premature component failure. The Aeroswift platform is a large volume AM machine where a high-temperature substrate preheating system is used to mitigate high thermal gradients. The current machine platform is unable to achieve a target build-plate temperature of 600 °C. This study focuses on the analysis of the preheating system design to determine the cause of its inefficiency, and the experimental testing of key components such as the heater and insulation materials. A Finite Element Analysis (FEA) model shows the ceramic heater achieves a maximum temperature of 395 °C, while the substrates (build-plates) only attain 374 °C. Analysis showed that having several metal components in contact and inadequate insulation around the heater caused heat loss, resulting in the preheating system’s inefficiency. Additionally, experimental testing shows that the insulation material used was 44% efficient, and a simple insulated test setup was only able to obtain a maximum temperature of 548.8 °C on a 20 mm thick stainless steel 304 plate, which illustrated some of the challenges faced by the current pre-heating design. New design options have been developed and FEA analysis indicates that a reduction in heat loss through improved sub-component configurations can obtain 650 °C degrees above the substrate without changing the heating element power. The development and challenges associated with the large-scale preheating system for AM are discussed, giving an insight into improving its performance.

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Effect of high-temperature preheating on pure copper thick-walled samples processed by laser powder bed fusion

Cited by 22 publications

References 35 publications

Fabrication of metal-ceramic substrates by laser powder bed fusion using a high-power green laser and high temperature preheating

Fabrication of metal-ceramic substrates by laser powder bed fusion using a high-power green laser and high temperature preheating

Effect of Preheating on the Residual Stress and Material Properties of Inconel 939 Processed by Laser Powder Bed Fusion

Evaluation of a High-Temperature Pre-Heating System Design for a Large-Scale Additive Manufacturing System

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