Abstract:Metal powders are components with multidisciplinary usage as their application is very broad. Their consistent characterization across all disciplines is important for ensuring repeatable and trouble-free processes. Ten metal powders were tested in the study. In all cases, the particle size distribution and morphology (scanning electron microscope-SEM photos) were determined. The aim of this work was to inspect the flow behavior of metal powders through another measured characteristic, namely the angle of inte… Show more
“…Shear force is applied by the rotating chamber of the apparatus, and the torque is transmitted by two rods which are fixed onto the shear lid during the rotational measurement test. Figure 3 45 shows a powder yield locus obtained from measurements on a RST, which contains a great deal of important information, including the linearized angle of internal friction ϕ , cohesion c , effective angle of internal friction (AIFE), major consolidation stress σ 1 and the unconfined yield strength σ c . Figure 3 Schematic diagram of powder yield locus obtained from the Schulze ring tester 45 .…”
Section: Methodsmentioning
confidence: 99%
“…The density for the given measurement is achieved through consolidation (compaction) at a defined strength load. Shear force is applied by the rotating chamber of the apparatus, and the torque is transmitted by two rods 45 shows a powder yield locus obtained from measurements on a RST, which contains a great deal of important information, including the linearized angle of internal friction ϕ, cohesion c, effective angle of internal friction (AIFE), major consolidation stress σ 1 and the unconfined yield strength σ c . The AIFE was measured for each metal powder 10 times for 10,000 Pa normal stress settings.…”
Section: Shear Cell Procedures-aife and Flow Indexmentioning
confidence: 99%
“…Schematic diagram of powder yield locus obtained from the Schulze ring tester45 . https://doi.org/10.1038/s41598-020-77974-3…”
With the rise of additive technologies, the characterization of metal powders is increasingly required. There is a need to precisely match the properties of metal powders to a specific machine and to ensure highly consistent production. Therefore, the study aims at a detailed characterization of ten metal powders (Metal powder 316 L, Zn, Sn, Al, Cu, Mn, Fe, Bronze, Ti and Mo powder), for which the particle size distribution, morphology, static and dynamic angle of repose and the effective internal friction angle (AIFE) were determined. The AIFE parameter and flow index were determined from three commonly used rotary shear devices: The computer-controlled Ring Shear Tester RST-01. pc, the Brookfield PFT Powder Flow Tester and the FT4 Powder rheometer. The results showed that the values for the device of one manufacturer did not fully correspond to the values of another one. The flow characteristics of the metal powders were quantified from the particle size distribution data, static angle of repose, and AIFE data. According to the particle size distribution and angle of repose (AOR), 50% of the tested metal powders fell into the free-flowing mode. According to the evaluation of AIFE, 20% of the samples fell into the lower area. Based on the flow indexes calculated from the measurements of the shear devices used, 100% (RST-01.pc), 70% (PFT) and 50% (FT4) of the samples were included in the free-flowing category. When comparing the results, attention should be paid not only to the nature of the material, but also to the methodology and equipment used. A comparison of methodologies revealed similarities in the changing behavior of the different metal powders. A comparison of effective angles of AIFE and static AOR was shown, and a hypothesis of the conversion relation was derived.
“…Shear force is applied by the rotating chamber of the apparatus, and the torque is transmitted by two rods which are fixed onto the shear lid during the rotational measurement test. Figure 3 45 shows a powder yield locus obtained from measurements on a RST, which contains a great deal of important information, including the linearized angle of internal friction ϕ , cohesion c , effective angle of internal friction (AIFE), major consolidation stress σ 1 and the unconfined yield strength σ c . Figure 3 Schematic diagram of powder yield locus obtained from the Schulze ring tester 45 .…”
Section: Methodsmentioning
confidence: 99%
“…The density for the given measurement is achieved through consolidation (compaction) at a defined strength load. Shear force is applied by the rotating chamber of the apparatus, and the torque is transmitted by two rods 45 shows a powder yield locus obtained from measurements on a RST, which contains a great deal of important information, including the linearized angle of internal friction ϕ, cohesion c, effective angle of internal friction (AIFE), major consolidation stress σ 1 and the unconfined yield strength σ c . The AIFE was measured for each metal powder 10 times for 10,000 Pa normal stress settings.…”
Section: Shear Cell Procedures-aife and Flow Indexmentioning
confidence: 99%
“…Schematic diagram of powder yield locus obtained from the Schulze ring tester45 . https://doi.org/10.1038/s41598-020-77974-3…”
With the rise of additive technologies, the characterization of metal powders is increasingly required. There is a need to precisely match the properties of metal powders to a specific machine and to ensure highly consistent production. Therefore, the study aims at a detailed characterization of ten metal powders (Metal powder 316 L, Zn, Sn, Al, Cu, Mn, Fe, Bronze, Ti and Mo powder), for which the particle size distribution, morphology, static and dynamic angle of repose and the effective internal friction angle (AIFE) were determined. The AIFE parameter and flow index were determined from three commonly used rotary shear devices: The computer-controlled Ring Shear Tester RST-01. pc, the Brookfield PFT Powder Flow Tester and the FT4 Powder rheometer. The results showed that the values for the device of one manufacturer did not fully correspond to the values of another one. The flow characteristics of the metal powders were quantified from the particle size distribution data, static angle of repose, and AIFE data. According to the particle size distribution and angle of repose (AOR), 50% of the tested metal powders fell into the free-flowing mode. According to the evaluation of AIFE, 20% of the samples fell into the lower area. Based on the flow indexes calculated from the measurements of the shear devices used, 100% (RST-01.pc), 70% (PFT) and 50% (FT4) of the samples were included in the free-flowing category. When comparing the results, attention should be paid not only to the nature of the material, but also to the methodology and equipment used. A comparison of methodologies revealed similarities in the changing behavior of the different metal powders. A comparison of effective angles of AIFE and static AOR was shown, and a hypothesis of the conversion relation was derived.
“…From the normal and shear stress points a yield locus was created. The Angle of internal friction is the tangent of the linearized yield locus [25]. The higher the AIF value, the smaller the interparticular forces, and the more flowable the powder.…”
This paper investigates the Angle of Repose (AoR) of powder materials with respect to their morphological and rheological properties. Glass beads, sand, flour and semolina of different particle sizes were used as the experimental materials. The investigated material was analysed with respect to particle shape and size. The rheological properties of the material were obtained by a shear cell test. The AoR was analysed in terms of cohesion, bulk density, particle size and circularity. More cohesive materials such as the flour samples exhibited the largest AoR > 40°, indicating their poor flowability. Glass bead samples with a high circularity value had significantly lower AoR than the flour. The Angle of Internal Friction values were not dependent on those of the AoR. Using a dimensional analysis, a mathematical model was developed to determine the AoR values based on the material properties. By the application of this model, highly accurate calculation of the value of AoR is made possible.
“…Existem dois fatores principais que devem ser avaliados, o primeiro sendo a morfologia e distribuição de tamanho de partícula. Os processos de manufatura aditiva requerem que as partículas sejam esféricas e com distribuição de tamanho relativamente larga, garantindo boa fluidez e empacotamento no momento de formação da camada de pó [8]. A presença de contaminantes na forma de partículas-satélite ou inclusões é um segundo fator de importância, pois não apenas podem levar a alterações na composição química global do material, como também impactar de forma deletéria nas propriedades mecânicas da peça final [9].…”
Resumo: O presente trabalho teve como objetivo a determinação dos parâmetros ótimos do processo de manufatura aditiva de Fusão Seletiva a Laser (FSL) para o aço 316L visando a obtenção de peças com alta densidade, utilizando equipamento fabricado no Brasil. Foi realizada também uma completa caracterização estrutural tanto da matéria prima utilizada (pó comercial) quanto das peças mais densas obtidas. As propriedades mecânicas das peças produzidas por FSL também foram avaliadas e comparadas com peça fabricada de forma convencional. Foi observado que a densidade das peças aumenta com o aumento da densidade volumétrica de energia fornecida pelo laser até atingir um patamar de máxima densidade. Um modelo polinomial foi proposto correlacionando a densidade volumétrica de energia utilizada com a densidade final da peça. As peças produzidas por FSL mostraram uma elevada densificação (densidade relativa superior a 99,49%) com uma reduzida porosidade homogeneamente dispersa no material. Uma microestrutura austenítica celular, típica do processo FSL, foi obtida. A dureza e a microestrutura das peças se mostrou constante ao longo do comprimento das mesmas e os resultados obtidos em ensaio de compressão mostraram que as peças obtidas por FSL possuem uma resistência mecânica e ductilidade próximas às observadas para amostra fabricada de forma convencional.
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