Powder particles with spherical geometries have been found to result in better powder performance in different industries, especially Additive Manufacturing (AM), by fabricating more dense powder ...layers that consequently result in more desirable part properties with less defects. Plasma spheroidization process has shown an excellent capability in enhancing particle geometries of powders from a variety of materials, particle size distributions, and arbitrary initial particle geometries. The current review paper summarizes the previous conducted work on plasma spheroidization process to determine the effect of its process parameters on powder characteristics. The spheroidization process parameters, including powder feed rate, central, carrier, and sheath gas flow rates, gas mixtures, power, and chamber pressure are individually discussed. Also, the impact of these process parameters on powder characteristics, such as particle size distribution, particle trajectories, chemical impurity, microstructure, porosity, flowability, and densities are reviewed. A tradeoff among process parameters, spheroidization ratio, and evaporation rate was observed. Depending on particle size and material melting point, increasing particle residence time in exposure to plasma first increased and then decreased the spheroidization ratio overall.
•A comprehensive review on powder plasma spheroidization process.•Effects of spheroidization parameters on powder characteristics have been summarized.•Improvement of powder performance through reshaping irregular particles to spheres.•A tradeoff exists among spheroidization parameters, spheroidization, and evaporation.•Increasing residence time first increased and then decreased spheroidization overall.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Laser-Powder Bed Fusion (LPBF) has been extensively utilized by a broad range of manufacturing industries in recent years. Fabricating parts with high mechanical properties and smooth surfaces has ...motivated such industries and academic communities to study different aspects and steps of the LPBF process, including powder spreading, laser scanning, and solidification. Creation of highly dense
powder
layers with lower surface roughness before laser scanning step is a must for producing non-porose
part
layers after laser scanning step of LPBF process. Thus, the initial powder spreading step of the LPBF process has been investigated to correlate the powder spreadability to powder layer quality and consequent part properties. The current review paper summarizes the previous work performed to define some spreadability metrics and determine the impact of LPBF process parameters and powder characteristics on powder spreadability. The spread powder layer's quality, which is called powder spreadability, is discussed in terms of empty areas on the substrate, powder bed density, powder surface roughness, powder dynamic repose angle, and powder mass flow rate. Also, the influence of LPBF process parameters, including recoating velocity, layer thickness, and recoater type, and powder characteristics, like particle size distribution, on the defined spreadability metrics are reviewed.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Additive manufacturing (AM) can be deployed for space exploration purposes, such as fabricating different components of robots’ bodies. The produced AM parts should have desirable thermal and ...mechanical properties to withstand the extreme environmental conditions, including the severe temperature variations on the moon or other planets, which cause changes in parts’ strengths and may fail their operation. Therefore, the correlation between operational temperature and mechanical properties of AM fabricated parts should be evaluated. In this study, three different types of polymers, including polylactic acid (PLA), polyethylene terephthalate glycol (PETG), and acrylonitrile butadiene styrene (ABS), were used in the fused deposition modeling (FDM) process to fabricate several parts. The mechanical properties of produced parts were then investigated at various temperatures to generate knowledge on the correlation between temperature and type of material. When varying the operational temperature during tensile tests, the material’s glass transition temperature was found influential in determining the kind of material failure. ABS showed the best mechanical properties among the materials used at all temperatures due to its highest glass transition temperatures. The statistical analysis results indicated the temperature as the significant factor on tensile strength while the type of material was not a significant factor.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The use of gas-atomized powder as the feedstock material for the laser powder bed fusion (LPBF) process is common in the additive manufacturing (AM) community. Although gas-atomization produces ...powder with high sphericity, its relatively expensive production cost is a downside for application in AM processes. Water atomization of powder may overcome this limitation due to its low cost relative to the gas-atomization process. In this work, gas- and water-atomized 304L stainless steel powders were morphologically characterized through scanning electron microscopy (SEM). The water-atomized powder had a wider particle size distribution and exhibited less sphericity. Measuring powder flowability using the Revolution Powder Analyzer (RPA) indicated that the water-atomized powder had less flowability than the gas-atomized powder. Through examining the mechanical properties of LPBF fabricated parts using tensile tests, the gas-atomized powder had significantly higher yield tensile strength and elongation than the water-atomized powder; however, their ultimate tensile strengths were not significantly different.
Purpose
This paper aims to present the development and experimental study of a fully automated system using a novel laser additive manufacturing technology called laser foil printing (LFP), to ...fabricate metal parts layer by layer. The mechanical properties of parts fabricated with this novel system are compared with those of comparable methodologies to emphasize the suitability of this process.
Design/methodology/approach
Test specimens and parts with different geometries were fabricated from 304L stainless steel foil using an automated LFP system. The dimensions of the fabricated parts were measured, and the mechanical properties of the test specimens were characterized in terms of mechanical strength and elongation.
Findings
The properties of parts fabricated with the automated LFP system were compared with those of parts fabricated with the powder bed fusion additive manufacturing methods. The mechanical strength is higher than those of parts fabricated by the laser powder bed fusion and directed energy deposition technologies.
Originality/value
To the best knowledge of authors, this is the first time a fully automated LFP system has been developed and the properties of its fabricated parts were compared with other additive manufacturing methods for evaluation.
The success of laser-foil-printing (LFP) additive manufacturing depends critically on the laser welding of sheet metals onto the substrate or the previous layer during the part fabrication process. ...The welding can be generally categorized into two modes: conduction mode and keyhole mode. In this study, 304L stainless steel parts fabricated by the LFP process using the two laser welding modes are compared. The porosity, microstructure, and tensile properties of the fabricated parts in these two modes are measured and compared in the laser scanning direction (
X
) and part building direction (
Z
). The parts fabricated in the conduction mode have a higher density than those fabricated in the keyhole mode. On the tensile properties, both yield strength (YS) and ultimate tensile strength (UTS) have insignificant differences statistically based on the ANOVA analysis between the tensile specimens fabricated with the two welding modes by the LFP process. However, the conduction-mode parts have higher elongation than the keyhole-mode parts in both the
X
and
Z
directions, and the difference is especially significant in the
Z
direction. By using the electron backscattered diffraction (EBSD), it was found that the much higher ductility for the conduction-mode parts in the
Z
-axis direction is mainly due to the distinct grain boundary interface density in the
Z
-axis direction between the two welding modes.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The present study investigates the feasibility of producing strong and defect-free joints between 1050 aluminum and pure copper sheets by micro-friction stir welding using traditional and new tools. ...Many variables affect the quality of these types of joints that the parameters of rotational speed, welding speed, and tool offset are considered the main variables. The Taguchi method and analysis of variance were used to design the experiments and evaluate the obtained results. By analyzing the results of the tensile test and signal-to-noise analysis, the average maximum ultimate tensile strength of the joints is reported to be 88 MPa, when using the parameters of rotational speed, welding speed, and offset of the tool with levels of 2400 rpm, 40 mm/min, and 0.25 mm. The analysis of variance also showed that the parameters of rotational speed and welding speed, respectively, had the most significant effect on the tensile strength of the joints. The maximum and minimum values obtained from the microhardness test were recorded for the weld nugget zone and the heat-affected zone of aluminum, respectively, which are equal to 192 HV and 21 HV. Also, by performing sanding operations, the roughness of the joints is significantly reduced. The x-ray diffraction test results on optimal samples showed the presence of intermetallic compounds CuAl
2
and Cu
9
Al
4
in the welding area. The tensile strength of the joints created is strongly dependent on the formation of these intermetallic compounds.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Display omitted
•Copper powder in the forms of virgin, recycled, and oxygen-reduced were spheroidized.•Powder recycled in additive manufacturing was reset to virgin condition.•For the first time in ...literature, powder re-spheroidization was conducted.•The impact of plasma spheroidization on the morphology and oxygen impurity of powders was investigated.
Fabrication of parts with high mechanical properties heavily depend on the quality of powder deployed in the fabrication process. Copper powder in three different powder types were spheroidized using radio-frequency inductively coupled plasma (ICP) spheroidization process (TekSphero-15 system). The characterized powders include virgin powder as purchased from the powder manufacturer, powder used in electron beam powder bed fusion (EB-PBF) process, and reconditioned powder, which was used powder that underwent an oxygen-reduction treatment. The goal of spheroidizing these powder types was to evaluate the change in powder morphology, the possibility of enhancing the powder properties back to their as-received conditions, and assess oxygen reduction of the powder lots given their initial oxygen contents. Also, to investigate the impact of re-spheroidization on powder properties, the second round of spheroidization was performed on the already used-spheroidized powder. The impact of powder type on powder sphericity and particle size distribution was evaluated using the image analysis of scanning electron microscope (SEM) micrographs and laser diffraction, respectively. The spheroidized powder showed higher sphericity and more uniform particle size distribution overall. Depending on the powder collection bin, second round of spheroidization affected the powder sphericity differently. The possibility of deploying the plasma spheroidization process as an alternative oxygen-reduction technique was also investigated through tracking the powders’ oxygen content using inert gas fusion method before and after the spheroidization. The plasma spheroidized powder showed less oxygen content than the hydrogen-treated powder. The second round of spheroidization caused no change in oxygen content. The correlation between oxygen-reduction and created cracks was discussed and compared between plasma spheroidization and hydrogen-treatment. The plasma spheroidization process created a powder with higher sphericity, uniform particle size, and less oxygen content.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The widespread use of additive manufacturing (AM) has been extensively progressed in the past decade due to the convenience provided by AM in rapid and reliable part production. Fused deposition ...modeling (FDM) has witnessed even faster growth of application as its equipment is environmentally friendly and easily adaptable. This increased use of FDM to manufacture prototypes and finished parts is accompanied by concerns that 3D printed parts do not perform the same as relatively homogeneous parts produced by molding or machining. As the interface between two faces of bonded material may be modeled by stress elements, in theory, by modeling 3D printed layers subjected to tension at varying angles as transformed stress elements, the stress required to break the layer bonds can be determined. To evaluate such a relationship, in this study, the stresses calculated from stress transformation were compared with the behavior of 3D printed specimens subjected to tensile loads. The maximum principal stress was found to be constant relative to the layer angle, regardless of whether the specimen experienced failure at the layer interface or within the layer material, although the specimens with layers 75° relative to the load were notable exceptions to this finding. This failure at much lower stresses for the samples used in the 75° tests may be attributed to a possible environmental factor, such as temperature or humidity change, degrading the samples’ structural integrity.
Full text
Available for:
DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Laser Foil Printing (LFP) is a novel recently developed Additive Manufacturing (AM) process that fabricates components using metal foils in a layer-by-layer fashion. LFP process has found to perform ...better than some other well-known AM methods, such as Laser Powder Bed Fusion (LPBF), especially for challenging materials, like aluminum alloys, due to the high oxidation level of aluminum powders during melting and solidification steps of LPBF process. Deployment of foil format feedstock in LFP alleviates such challenges by removing powder material utilization. The properties of LFP fabricated parts are found to be strongly influenced by the melt pool depths, created during laser welding step of LFP process. The melt pool depths themselves are dominated by LFP’s process parameters, such as laser power and scan speed. Therefore, the correct selection of process parameter values is necessary for fabricating parts with desirable properties. In this work, some aluminum parts were fabricated using LFP with various levels of laser power and scan speed and their melt pool depths were measured. By conducting a thorough statistical analysis on the results, the dependency of created melt pool depths on these process parameters is evaluated. An empirical model is also developed that can accurately predict the yielding melt pool depths as a function of given values per laser power and scan speed. The developed model’s fit level to experimental results is examined to validate the accuracy of predicted results.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
