Microstructural coarsening of 6061 aluminum alloy semi-solid billets prepared via recrystallization and partial melting

Preparation of semi-solid microstructure with less liquid content of 7A09 aluminum alloy industrial extrusion billets is studied in this paper. In the treatment, melting-stirring and predeformation of the alloy billets are not required. The influences of different heating temperatures and insulation time on the microstructure evolution are studied and the obtained microstructure is observed and analyzed by optical microscopy. The results indicate that a fine microstructure can be obtained with the proposed process and the processing parameters can be controlled over a wide range. The liquid content can be controlled within a certain range.

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Semi-Solid 6061 Aluminum Alloy Slurry Prepared by Serpentine Channel Pouring Process and its Rheo-Diecasting

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.327.279 ◽

2022 ◽

Vol 327 ◽

pp. 279-286

Author(s):

Nai Yong Li ◽

Wei Min Mao ◽

Xiao Xin Geng ◽

Peng Yu Yan

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Aluminum Alloy ◽

Ductile Fracture ◽

Fracture Mechanism ◽

Pouring Temperature ◽

6061 Aluminum Alloy ◽

Serpentine Channel ◽

Die Cast ◽

Semi Solid

Semi-solid 6061 aluminum alloy slurry was prepared by a graphite serpentine channel and its rheo-diecasting experiment was carried out on the slurry. The influence of pouring temperature on the microstructure evolution and mechanical properties of the rheo-diecasting were investigated. The microstructure and fracture mechanism of traditional die cast tensile specimens and rheo-diecast tensile specimens were compared and investigated. The results indicate that the microstructure of rheo-diecast tensile specimens is composed of spherical primary α-Al grains and fine secondary solidified α2-Al grains. When the pouring temperature increased from 660 °C to 720 °C, the average equivalent grain diameter of primary α-Al grains increased from 42 μm to 58 μm, and the shape factor decreased from 0.82 to 0.73. As the pouring temperature increases, the as-cast tensile strength and elongation of tensile specimens both increase first and then decrease. When the pouring temperature was 690 °C, the best mechanical properties were obtained, with as-cast tensile strength of 142.93 MPa and as-cast elongation of 4.86%. The fracture mechanism of traditional die casting is mainly ductile fracture, and the fracture mechanism of rheo-diecasting is a mixed fracture of intergranular fracture and ductile fracture.

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Effect of Serpentine Channel Pouring Process on the Microstructure of Semi-Solid 6061 Aluminum Alloy Slurry

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.327.255 ◽

2022 ◽

Vol 327 ◽

pp. 255-262

Author(s):

Nai Yong Li ◽

Wei Min Mao ◽

Xiao Xin Geng ◽

Peng Yu Yan

Keyword(s):

Grain Size ◽

Aluminum Alloy ◽

Shape Factor ◽

Primary Phase ◽

High Quality ◽

Pouring Temperature ◽

6061 Aluminum Alloy ◽

Serpentine Channel ◽

Channel Surface ◽

Semi Solid

The semi-solid slurry of 6061 aluminum alloy was prepared by the serpentine channel pouring process. The influence of graphite serpentine channel and copper serpentine channel on the slurry was comparative analyzed. The effect of pouring temperature on the slurry microstructure was also investigated. The results indicate that both copper and graphite serpentine channel can be used to prepare semi-solid slurry with spherical primary grains. Compared with a permanent casting, the microstructure of the semi-solid slurry was significantly improved and refined. With the increase of pouring temperature, the average equivalent grain diameter of the primary phase grains in the semi-solid slurry increases gradually, but the shape factor decreases gradually. When the pouring temperature increased from 675 °C to 690 °C, a high quality semi-solid slurry can be obtained. Comparing the two kinds of serpentine channel, it is found that the copper serpentine channel can make the primary grains finer, and the average equivalent grain size was 63 μm. However, the solidified shell near the inner graphite serpentine channel surface was thinner than that of the copper serpentine channel. In conclusion, the graphite serpentine channel is more suitable for preparing semi-solid 6061 aluminum alloy slurry.

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Microstructural Evolution of ZL104 Aluminum Alloy Semi-Solid Billet Fabricated by RAP Process

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.285.234 ◽

2019 ◽

Vol 285 ◽

pp. 234-239

Author(s):

Yong Fei Wang ◽

Sheng Dun Zhao ◽

Chao Chen ◽

Peng Dong ◽

Peng Zhang

Keyword(s):

Aluminum Alloy ◽

Ostwald Ripening ◽

Isothermal Holding ◽

Isothermal Treatment ◽

Liquid Droplets ◽

Microstructural Coarsening ◽

Average Grain Size ◽

Cold Rolled ◽

Semi Solid ◽

Holding Temperature

In this study, ZL104 aluminum alloy supplied in cold rolled state was introduced in recrystallization and partial melting (RAP) process to fabricate semi-solid billets. During the RAP process, samples cut from cold rolled ZL104 aluminum plate were heated to different semi-solid temperatures, and the effects of isothermal treatment parameters on the microstructures of semi-solid billets were investigated. Results showed that, with the increase of isothermal holding temperature and time, both the average grain size and the shape factor were increased. Namely, the shape of solid grain was more and more spherical, but the size of solid grain was larger and larger, which may be not suitable for semi-solid forming. The size of liquid droplets was increased while the number of liquid droplets was decreased with increasing the isothermal holding temperature and time. Microstructural coarsening of solid grain were attributed to coalescence and Ostwald ripening mechanisms, however, the latter one played a more and more important role with the increase of isothermal holding time and temperature. Additionally, The optimal isothermal holding temperature and time are 570 °C and 5 min, respectively, and the coarsening rate constant is 1357.2 μm3/s at 570 °C.

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Influence of Solution Heat Treatment Temperature and Time on the Microstructure and Mechanical Properties of Gas Induced Semi-Solid (GISS) 6061 Aluminum Alloy

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.313-314.67 ◽

2013 ◽

Vol 313-314 ◽

pp. 67-71 ◽

Cited By ~ 2

Author(s):

Nitikarn Pajaroen ◽

Thawatchai Plookphol ◽

Jessada Wannasin ◽

Sirikul Wisutmethangoon

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Aluminum Alloy ◽

Treatment Condition ◽

Solution Heat Treatment ◽

Heat Treatment Condition ◽

Eutectic Phase ◽

6061 Aluminum Alloy ◽

Semi Solid ◽

Optimum Solution

The influence of solution heat treatment (SHT) temperature and time on the microstructure and mechanical properties of semi-solid 6061 aluminum alloy has been investigated in this study. Microstructure of the as-cast 6061 aluminum alloy mainly consisted of globular α-Al matrix and eutectic phase (α-Al + Mg2Si) at the grain boundary (GB). Iron rich intermetallic phase was also observed at the grain boundary. Eutectic phase started to dissolve after solution heat treatment. The dissolution of eutectic phase increased with increasing solution treatment time, however, the amount of remaining eutectic phase was found to be slightly changed after solution treating longer than 1 h at 550 °C and 2 h at 530 °C. Hardness and tensile results of specimens after artificial aging were utilized to compare and select the optimum solution heat treatment condition cooperating with the microstructural observation. The optimum solution heat treatment condition of the alloy in this study was at 530 °C for 2 h.

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