Selective laser melting of Al7050 powder: Melting mode transition and comparison of the characteristics between the keyhole and conduction mode

Qi, Ting; Zhu, Haihong; Zhang, Hu; Yin, Junhui; Liu, Ke; Zeng, Xiaoyan

doi:10.1016/j.matdes.2017.09.014

Cited by 272 publications

(93 citation statements)

References 27 publications

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“…The reason for this phenomenon is that the excessive energy input causes the metal evaporation. Simultaneously, the surface tension and the static pressure of the liquid phase metal are less than the metal vapor recoil pressure . So the weld pool depth becomes deeper at higher VED.…”

Section: Discussionmentioning

confidence: 98%

Selective Laser Melting of Gas Atomized Al–3.02Mg–0.2Sc–0.1Zr Alloy Powder: Microstructure and Mechanical Properties

Li¹,

Chen²,

Chen³

et al. 2018

Adv Eng Mater

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Additive manufactured Sc modified Al alloys for lightweight application is now arousing widespread attraction. The selective laser melting (SLM) of gas atomized Al-3.02Mg-0.2Sc-0.1Zr powder is studied, with the emphasis on its densification, microstructure, and properties. The intrigued finding is that the very high elongation-to-failure of 32.5% is obtained with medium tensile strength of 373 MPa after heat treatment of SLM sample. The average relative density is about 98.3% at a volumetric energy density range of (VED) 42-111 J mm À3 . The microstructure of produced sample shows cracks but it can be inhibited by increasing the VED. At an excessive VED, the weld pool is transformed from heat conduction to keyhole mode owing to the metal evaporation. Nano-sized Al 3 (Sc,Zr) precipitates with a diameter of 5-50 nm are observed, which is responsible for the main strengthening mechanism. The underlying mechanisms of metallurgical defects, weld pool mode and mechanical properties are also illuminated. Figure 3. Optical micrographs of polished SLM samples from horizontal section at different VEDs: a) 42 J mm À3 , b) 52 J mm À3 , c) 63 J mm À3 , d) 73 J mm À3 , e) 83 J mm À3 , and f) 100 J mm À3 .

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Section: Discussionmentioning

confidence: 98%

Selective Laser Melting of Gas Atomized Al–3.02Mg–0.2Sc–0.1Zr Alloy Powder: Microstructure and Mechanical Properties

Li¹,

Chen²,

Chen³

et al. 2018

Adv Eng Mater

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show abstract

“…Such difference in particle size, shape and distribution at melt pool boundaries when compared to those within the core of melt pools may be rationalised by the cooling rate gradient within each melt pool. Melt pool boundaries experience lower cooling rates than the core of melt pools [5,7,[16][17]58], and thus may resulting in greater solute rearrangement at the boundaries (although noting that the attendant cooling rates are likely to significantly inhibit diffusion).…”

Section: Scanning Electron Microscopy Analysismentioning

confidence: 99%

“…Metal additive manufacturing (AM) is a promising technology for complex and netshape prototyping and production, with minimal waste generation [1][2][3][4][5]. With the prospect of net shape production of high strength aluminium (Al) alloys [6][7][8][9][10][11][12], the interest in AM technology to produce components from high strength 7xxx series (Al-Zn-Mg(-Cu)) Al-alloys is increasing [6,[13][14][15][16][17][18]. To date, the microstructural evolution and corrosion behaviour of AM prepared 7xxx series Al-alloys have not been studied and hence not understood in contrast to wrought 7xxx series Al-alloys presently used in aerospace applications.…”

Section: Introductionmentioning

confidence: 99%

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Microstructure and corrosion evolution of additively manufactured aluminium alloy AA7075 as a function of ageing

Gharbi

Kairy

et al. 2019

npj Mater Degrad

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Additively manufactured high strength aluminium (Al) alloy AA7075 was prepared using selective laser melting (SLM). High strength Al-alloys prepared by SLM have not been widely studied to date. The evolution of microstructure and hardness, with the attendant corrosion, were investigated. Additively manufactured AA7075 was investigated both in the "as-produced" condition and as a function of artificial ageing. The microstructure of specimens prepared was studied using electron microscopy.Production of AA7075 by SLM generated a unique microstructure, which was altered by solutionising and further altered by artificial ageingresulting in microstructures distinctive to that of wrought AA7075-T6. The electrochemical response of additively manufactured AA7075 was dependent on processing history, and unique to wrought AA7075-T6, whereby dissolution rates were generally lower for additively manufactured AA7075. Furthermore, immersion exposure testing followed by microscopy, indicated different corrosion morphology for additively manufactured AA7075, whereby resultant pit size was notably smaller, in contrast to wrought AA7075-T6.

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“…Much research has been performed on processing the most often used 4XXX series such as Al–12Si, and AlSi–10Mg . While for structural applications 6XXX or 7XXX series alloys are preferred, research has demonstrated that such alloys offer significant processing challenges, for example, due to process‐related cracking phenomena . While advances have been made, significant issues also persist for SLM‐processed aluminum alloys regarding the trade‐off between material strength and anisotropy, especially for 4XXX alloys.…”

mentioning

confidence: 99%

Mechanical Anisotropy Investigated in the Complex SLM‐Processed Sc‐ and Zr‐Modified Al–Mg Alloy Microstructure

et al. 2018

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Additive manufactured Sc-modified aluminum alloys hold great promise for aerospace components under high and/or complex loads. While the thermal patterns formed in the melt pool during selective laser melting (SLM) of the powdered material result in a complex microstructure featuring a bimodal grain size distribution, such alloys show an isotropic mechanical response during mm-scale testing. To understand the role of microstructure on the mechanical response, nanoindentation is performed on SLM-processed Scalmalloy 1 for both the untreated and precipitate-hardened alloy, studied both parallel and orthogonal to the build direction. The elastic modulus of the coarse and fine grained regions is significantly greater than the macro-scale modulus of the material, suggesting macroscopic control over the elastic performance. With negligible influence over the elastic properties, there is a significant correlation between the grain size distribution and the nanoindentation hardness. This weak but significant grain boundary strengthening is lost when applying load orthogonal to the build direction for the precipitate-hardened material. Hardness anisotropy is moreover observed in fine-grained regions for the as-processed sample. In contrast to the isotropy reported from larger-scale mechanical tests, the discrete microstructural zones deviate from ideal isotropic behavior, and this may have consequences for simulation and design of this alloy.

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Selective laser melting of Al7050 powder: Melting mode transition and comparison of the characteristics between the keyhole and conduction mode

Cited by 272 publications

References 27 publications

Selective Laser Melting of Gas Atomized Al–3.02Mg–0.2Sc–0.1Zr Alloy Powder: Microstructure and Mechanical Properties

Selective Laser Melting of Gas Atomized Al–3.02Mg–0.2Sc–0.1Zr Alloy Powder: Microstructure and Mechanical Properties

Microstructure and corrosion evolution of additively manufactured aluminium alloy AA7075 as a function of ageing

Mechanical Anisotropy Investigated in the Complex SLM‐Processed Sc‐ and Zr‐Modified Al–Mg Alloy Microstructure

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