Columnar to equiaxed transition during direct metal laser sintering of AlSi10Mg alloy: Effect of building direction

Hadadzadeh, Amir; Amirkhiz, Babak Shalchi; Li, Jian; Mohammadi, Mohsen

doi:10.1016/j.addma.2018.08.001

Cited by 78 publications

(46 citation statements)

References 58 publications

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“…The microstructure obtained in the three orientations can be appreciated in Figure 7, where OM images are illustrated next to FEG-SEM ones. A very fine cellular structure is observed, equiaxed in the XY plane ( Figure 7A) and elongated in the Z direction ( Figure 7B,C), comparable to the 'fibre texture' observed by Prashanth et al for Al-12Si [14] and by Hadadzadeh et al for AlSi10Mg [15]. Hadadzadeh and colleagues produced extremely interesting proofs that when the building direction changes from vertical to horizontal, a columnar to equiaxed transition is obtained in the AlSi10Mg alloy produced by LPBF.…”

Section: A357supporting

confidence: 77%

“…Specimens produced in the 90 • orientation are the strongest since they benefit from shear loads acting along the direction of the fine elongated grain structure. An additional effect of higher percentage of columnar grains in 90 • specimens as compared to 0 • ones, similar to the findings by Hadadzadeh et al [15], cannot be excluded. Other authors previously observed a mixed quasi-cleavage and dimpled morphology on the fracture surfaces of A356 tensile samples, in the as-cast condition or after T6, as well as of A357 produced by LPBF [18,19].…”

Section: Resultsmentioning

confidence: 59%

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Additive Manufactured A357.0 Samples Using the Laser Powder Bed Fusion Technique: Shear and Tensile Performance

Denti

2018

Metals

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New aluminium alloys, with lower silicon content than in the first-developed formulations, have recently been introduced in the field of Additive Manufacturing and are dedicated to automotive applications. As they are relatively new, mechanical characterization under standard protocols of the automotive field are of utmost scientific as well as industrial relevance. The paper addresses the mechanical properties and microstructure of A357.0. Static tensile and shear tests of samples built by Laser Powder Bed Fusion, with different orientations in the machine work volume, have been performed. The aim was to identify possible anisotropy in the tensile and shear behaviour of this innovative alloy. Particularly for shear, the effect of adhesion between the layers onto shear strength was studied. Results analysis, by means of statistical tools, allows for the affirmation that no tensile modulus or yield strength anisotropy is observed. Instead, a small (yet statistically significant) increase in both shear- and tensile strength and a decrease in ductility are obtained as the direction of the specimens approaches the growth direction. Scanning Electron Microscope (SEM) observation of the failure mechanisms assisted in the interpretation of the results, by relating different failure modes to the relative orientation of loads versus the directions of inherent anisotropy in Laser Powder Bed Fusion processes.

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Section: A357supporting

confidence: 77%

Section: Resultsmentioning

confidence: 59%

Additive Manufactured A357.0 Samples Using the Laser Powder Bed Fusion Technique: Shear and Tensile Performance

Denti

2018

Metals

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“…The SEM images of as-built strut samples with various build sizes are shown in Figure 6. The microstructure of the melt pool center was characterized with a fine cellular–dendritic microstructure in which a rich eutectic silicon network is distributed in the Al-matrix [31]. As shown in Figure 6, the morphologies of the cells of the melt pool center are different as the build size changes.…”

Section: Resultsmentioning

confidence: 99%

Study of Size Effect on Microstructure and Mechanical Properties of AlSi10Mg Samples Made by Selective Laser Melting

et al. 2018

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The macroscopic mechanical performance of additive manufactured structures is essential for the design and application of multiscale microlattice structure. Performance is affected by microstructure and geometrical imperfection, which are strongly influenced by the size of the struts in selective laser melting (SLM) lattice structures. In this paper, the effect of size on microstructure, geometrical imperfection, and mechanical properties was systemically studied by conducting experimental tests. A series of AlSi10Mg rod-shaped samples with various diameters were fabricated using SLM. The uniaxial tensile test results show that with the decrease in build diameter, strength and Young’s modulus of strut decreased by 30% more than the stable state. The main reasons for this degradation were investigated through microscopic observation and micro X-ray computed tomography (μ-CT). In contrast with large-sized strut, the inherent porosity (1.87%) and section geometrical deviation (3%) of ponysize strut is greater because of the effect of thermal transform and hydrogen evolution, and the grain size is 0.5 μm. The discrepancy in microstructure, geometrical imperfection, and mechanical properties induced by size effect should be considered for the design and evaluation of SLM-fabricated complex structures.

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“…Experimental verification of CET in AM processes include the results from Bermingham et al [41] who reported a mix of columnar and equiaxed grains in Ti-alloys with La 2 O 3 particles produced by a wire based AM process. Hadadzadeh et al [42] reported CET in an AlMgSi alloy under Direct Metal Laser Sintering (DMLS) being dependent on the build direction.…”

Section: Columnar To Equiaxed Transition (Cet) During Am Related Processesmentioning

confidence: 99%

Towards understanding grain nucleation under Additive Manufacturing solidification conditions

et al. 2020

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This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Columnar to equiaxed transition during direct metal laser sintering of AlSi10Mg alloy: Effect of building direction

Cited by 78 publications

References 58 publications

Additive Manufactured A357.0 Samples Using the Laser Powder Bed Fusion Technique: Shear and Tensile Performance

Additive Manufactured A357.0 Samples Using the Laser Powder Bed Fusion Technique: Shear and Tensile Performance

Study of Size Effect on Microstructure and Mechanical Properties of AlSi10Mg Samples Made by Selective Laser Melting

Towards understanding grain nucleation under Additive Manufacturing solidification conditions

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