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Microstructure and Properties of As-Cast and Heat-Treated 2017A Aluminium Alloy Obtained from Scrap Recycling.

ABSTRACT: The continuous increase in the consumption of aluminium and its alloys has led to an increase in the amount of aluminium scrap. Due to environmental protection, and to reduce the costs of manufacturing aluminum in recent years, a lot of research is devoted to recycling of aluminum alloys. The paper presents the results of research concerning the possibility of manufacturing standardized alloy 2017A from commercial and post-production scrap by continuous casting. Obtained from recycling process ingots were subjected to analysis of chemical composition and intermetallic phase composition. Based on the results of light microscopy (LM), scanning electron microscopy + electron dispersive spectroscopy (SEM + EDS), and X-ray diffraction (XRD) the following phases in the as-cast state were identified: ?-Al₂Cu, ?-Mg₂Si, Al₇Cu₂Fe, Q-Al₄Cu₂Mg₈Si₇, and ?-Al₁₅(FeMn)₃(SiCu)₂. During solution heat treatment most of the primary precipitates of intermetallic phases, like ?-Al₂Cu, ?-Mg₂Si, and Q-Al₄Cu₂Mg₈Si₇, were dissolved in the solid solution ?-Al, and during natural and artificial aging they precipitate as strengthening phases ?-Al₂Cu and Q-Al₄Cu₂Mg₈Si₇ with high dispersion. The highest hardness-150.3 HB-of 2017A alloy was obtained after solution heat treatment from 510 °C and aging at 175 °C. In the static tensile test the mechanical (R_m and R_p0.₂) and plastic (A₅) properties were determined for 2017A alloy in the cast state and after T4 heat treatment. The highest strength properties-tensile strength R_m = 450.5 MPa and yield strength R₀.₂ = 268.7 MPa with good relative elongation A₅ = 14.65%, were obtained after solution heat treatment at 510 °C/6 h/water quenching and natural aging at 25 °C for 70 h. The alloy manufactured from recycled scrap is characterized by relatively high mechanical properties.

SUBMITTER: Grazyna MN

PROVIDER: S-EPMC7795794 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature

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Microstructure and Properties of As-Cast and Heat-Treated 2017A Aluminium Alloy Obtained from Scrap Recycling.

Grażyna Mrówka-Nowotnik MN Gancarczyk Kamil K Nowotnik Andrzej A Dychtoń Kamil K Boczkal Grzegorz G

Materials (Basel, Switzerland) 20201227 1

The continuous increase in the consumption of aluminium and its alloys has led to an increase in the amount of aluminium scrap. Due to environmental protection, and to reduce the costs of manufacturing aluminum in recent years, a lot of research is devoted to recycling of aluminum alloys. The paper presents the results of research concerning the possibility of manufacturing standardized alloy 2017A from commercial and post-production scrap by continuous casting. Obtained from recycling process i ...[more]

PMID: 33375509

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Project description:The bimodal-grain-size 7075 aluminium alloys containing varied ratios of large and small 7075 aluminium powders were prepared by spark plasma sintering (SPS). The large powder was 100 ± 15 ?m in diameter and the small one was 10 ± 5 ?m in diameter. The 7075 aluminium alloys was completely densified under the 500 °C sintering temperature and 60 MPa pressure. The large powders constituted coarse grain zone, and the small powders constituted fine grain zone in sintered 7075 aluminium alloys. The microstructural and microchemical difference between the large and small powders was remained in coarse and fine grain zones in bulk alloys after SPS sintering, which allowed for us to investigate the effects of microstructure and microchemistry on passive properties of oxide film formed on sintered alloys. The average diameter of intermetallic phases was 201.3 nm in coarse grain zone, while its vale was 79.8 nm in fine grain zone. The alloying element content in intermetallic phases in coarse grain zone was 33% to 48% higher than that on fine grain zone. The alloying element depletion zone surrounding intermetallic phases in coarse grain zone showed a bigger width and a more severe element depletion. The coarse grain zone in alloys showed a bigger electrochemical heterogeneity as compared to fine grain zone. The passive film formed on coarse grain zone had a thicker thickness and a point defect density of 2.4 × 1024 m-3, and the film on fine grain zone had a thinner thickness and a point defect density of 4.0 × 1023 m-3. The film resistance was 3.25 × 105 ?cm2 on coarse grain zone, while it was 6.46 × 105 ?cm2 on fine grain zone. The passive potential range of sintered alloys increased from 457 mV to 678 mV, while the corrosion current density decreased from 8.59 × 10-7 A/cm2 to 6.78 × 10-7 A/cm2 as fine grain zone increasing from 0% to 100%, which implied that the corrosion resistance of alloys increased with the increasing content of fine grains. The passive film on coarse grain zone exhibited bigger corrosion cavities after pitting initiation compared to that on fine grain zone. The passive film formed on fine grain zone showed a better corrosion resistance. The protectiveness of passive film was mainly determined by defect density rather than the thickness in this work.

Dataset Information

Microstructure and Properties of As-Cast and Heat-Treated 2017A Aluminium Alloy Obtained from Scrap Recycling.

Publications

Microstructure and Properties of As-Cast and Heat-Treated 2017A Aluminium Alloy Obtained from Scrap Recycling.

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