Role of Mg2Si precipitates size in determining the ductility of A357 cast alloy

Asghar, Ghulam; Peng, Liming; Fu, Penghuai; Yuan, Lingyang; Liu, Yue

doi:10.1016/j.matdes.2019.108280

Cited by 51 publications

(15 citation statements)

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“…The sample hardness increased as a consequence of the DA heat treatment performed at 170 • C, reaching the highest value of 146 ± 5 HV after 6 h (DA-6). This trend was observed in many other studies [10,20]. The S-SHT sample had the lowest hardness value of all the tested samples (102 ± 5 HV).…”

Section: Hardnesssupporting

confidence: 85%

“…These are very important aspects in the L-PBF process as it makes it possible to reach full dense and crack-free parts [6][7][8]. The large interest in the AlSi7Mg alloy is proved by the large number of scientific papers available in the literature [9][10][11][12][13][14][15][16]. This alloy is also generally called A357 (AMS 4219 standard) or F357 (AMS 4289 standard) depending on the beryllium content, which is lower than 0.002% in the F357 standard.…”

Section: Introductionmentioning

confidence: 99%

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Short Heat Treatments for the F357 Aluminum Alloy Processed by Laser Powder Bed Fusion

et al. 2021

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Conventionally processed precipitation hardening aluminum alloys are generally treated with T6 heat treatments which are time-consuming and generally optimized for conventionally processed microstructures. Alternatively, parts produced by laser powder bed fusion (L-PBF) are characterized by unique microstructures made of very fine and metastable phases. These peculiar features require specifically optimized heat treatments. This work evaluates the effects of a short T6 heat treatment on L-PBF AlSi7Mg samples. The samples underwent a solution step of 15 min at 540 °C followed by water quenching and subsequently by an artificial aging at 170 °C for 2–8 h. The heat treated samples were characterized from a microstructural and mechanical point of view and compared with both as-built and direct aging (DA) treated samples. The results show that a 15 min solution treatment at 540 °C allows the dissolution of the very fine phases obtained during the L-PBF process; the subsequent heat treatment at 170 °C for 6 h makes it possible to obtain slightly lower tensile properties compared to those of the standard T6. With respect to the DA samples, higher elongation was achieved. These results show that this heat treatment can be of great benefit for the industry.

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Section: Hardnesssupporting

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Short Heat Treatments for the F357 Aluminum Alloy Processed by Laser Powder Bed Fusion

et al. 2021

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“…In addition to Cu, the addition of Mg has a great influence on the microstructure and properties of Al−Si alloys, Al 5 Cu 2 Mg 8 Si 6 , Mg 2 Si, and some other second phases are usually formed in Al−Si−Cu−Mg quaternary alloys in an as-cast state. The Mg 2 Si phase has a low density (1.90 g/cm 3 ), a high melting point (1087 • C), a high hardness (4.5 × 10 9 N/m 2 ), a high elastic modulus (120 GPa), and a low thermal expansion coefficient (7.5 × 10 −6 K −1 ) [7]. Therefore, the formation of Mg 2 Si is very important to the mechanical properties of hypereutectic Al−Si−Cu−Mg alloys.…”

Section: Introductionmentioning

confidence: 99%

Calculation Based on the Formation of Mg2Si and Its Effect on the Microstructure and Properties of Al–Si Alloys

Hao

Bian

et al. 2021

Materials

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In order to investigate the effect of Mg2Si formation on the microstructure and properties of an Al−Si alloy, the critical point of a hypereutectic Al−17Si−4Cu−Mg alloy was calculated by Pandat software. The calculation results of the equilibrium phase diagram show that the critical point for Mg2Si phase formation for the alloy was obtained when the Mg content was 2.2%. The contents of 0.5 wt.% Mg and 2.5 wt.% Mg were selected as the research object. The content of Mg increased from 0.5 wt.% to 2.5 wt.%, the eutectic Si in the matrix was reduced, and the Chinese character-like Mg2Si phase appeared in the microstructure. In the peak ageing state, in addition to θ″ and Q′ phases that were mainly precipitated, there was also needle-like β″ precipitation in the 2.5 wt.% Mg content alloy. Larger precipitates were found in 2.5 wt.% content alloys, mainly due to the promotion of the solid solution having the aggregation and segregation of more solute elements in the matrix. The tensile strength, elongation, and hardness of hypereutectic Al−17Si−4Cu−0.5Mg alloy under peak ageing were 331 MPa, 3.11%, and 152.1 HB, respectively. The tensile strength and the elongation decreased while the hardness increased with the 2.5 wt.% Mg content, which is due to the formation of hard and brittle Mg2Si and Al8FeMg3Si, which has a splitting effect on the matrix.

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“…Among the broad variety of Al-Si alloys, hypoeutectic A356/357 alloys are typically employed to produce wheels, chassis, manifolds, and cylinder blocks [5]. Optimum mechanical properties (especially a sustainable ductility) are aimed to achieve the desired functionality and performance of these parts/components [6].…”

Section: Introductionmentioning

confidence: 99%

Concurrent effects of various B additions on grain refinement, Fe intermetallics morphologies, and ductility evolution of Al-7.5Si-0.55 Mg (A357) cast alloy

et al. 2020

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Simultaneous effects of boron (B) additions on grain refinement, morphological changes in Fe-intermetallic compounds, and consequent variations in mechanical responses of the cast Al-7.50Si-0.55 Mg (A357) alloys are evaluated in this research work. The contents B are varied from 0.002 to 0.40 wt. % and subsequent changes in the grain size and Feintermetallics morphologies are assessed through polarized light images, optical micrography, and scanning electron microscopy. A small addition of B (0.04 wt. %) yields identical refinement result (620 µm) as noted for commercial grain refiner Al-5Ti-1B (642 µm); whereas, the higher amount (0.40 wt. % of B) reduces the grain size up to 44% (360 µm). In as-cast state, the structure of the π-Fe phase is transmuted from plate/needle-type to Chinese-script particles for increased quantities (0.10 ~ 0.40 wt. %) of B. Contrarily, the heat-treatment (T6) causes the depletion of Mg and B from the π-Fe phase Chinese-script morphologies and disintegrates them by creating segregated regions of Fe particles. These agglomerated areas of Fe particles act as stress concentration points during tensile loading and considerably decrease the ductility values from 6.7 to 1.8%. Therefore, it implies that great care must be taken while developing B containing grain refiners.

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Role of Mg2Si precipitates size in determining the ductility of A357 cast alloy

Cited by 51 publications

References 50 publications

Short Heat Treatments for the F357 Aluminum Alloy Processed by Laser Powder Bed Fusion

Short Heat Treatments for the F357 Aluminum Alloy Processed by Laser Powder Bed Fusion

Calculation Based on the Formation of Mg2Si and Its Effect on the Microstructure and Properties of Al–Si Alloys

Concurrent effects of various B additions on grain refinement, Fe intermetallics morphologies, and ductility evolution of Al-7.5Si-0.55 Mg (A357) cast alloy

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