Application of aluminum alloy in rheological casting

In the semi-solid processing of aluminum alloy casting more aluminum alloy, such as A356, A357, A380 and so on. Due to the wide solidification interval of cast aluminum alloy, it is more convenient to study the semi-solid pulping, but the comprehensive mechanical properties of the formed parts are relatively low. Forged aluminum alloy belongs to high strength aluminum alloy, which is widely used in aerospace, automobile and military industries. Its parts are generally produced by forging and extrusion and other plastic forming processes. Aluminum alloy forging or extrusion plastic forming can guarantee the strength and performance index of the parts, but its processing cost is high and it is difficult to produce the parts with complex shape. The traditional gravity casting, pressure casting and metal mold casting are used to forge aluminum alloy, and the defects such as hot cracking and insufficient filling are easy to occur. The semi-solid casting has opened up a new direction for the near net forming of forged aluminum alloy, which is also a new target for scholars at home and abroad. 2××× ×, 6××× × and 7××× × series alloys are mainly studied in the semi-solid forming of forged aluminum alloys. The thixoforming of aluminum alloy mentioned above is more studied. Because of its short process, high production efficiency, high efficiency and energy saving, and low production cost, rheological forming is an important development direction of semi-solid engineering application.

Fu Jia et al. studied the semi-solid rheological rolling process of A2017 aluminum alloy, and the experiment showed that the tensile strength of semi-solid A2017 alloy prepared by self-made inclined plate device for rheological rolling could reach 198.6MPa, and the elongation was 11.7%. Zhang Jun et al. carried out rheological die-casting of A356 aluminum alloy using self-developed TBR process, and the tensile strength and elongation of the semi-solid parts prepared reached 271 MPa and 7.3%. Wang Shuncheng et al. prepared A356 semi-solid slurry by mechanical stirring method and carried out rheological die forging forming. The results show that the tensile strength and elongation of the workpiece after rheological die forging forming is 261.7MPa and 4.1%, and that after T6 heat treatment, the tensile strength is 347.8MPa and elongation is 3.2%. Chen Zhengzhou et al prepared the tensile specimen of A356 aluminum alloy by SCRC technique. The tensile strength could reach 250MPa, and the elongation was 8.6%-13.2%. After T6 treatment, the tensile strength increased by 30% to about 325 MPa, and the elongation decreased slightly. R.G. Guan et al. formed A356 aluminum alloy by rheological extrusion casting, and the tensile strength of the formed parts reached 232MPa and the elongation was 7%. Qi Mingfan et al. studied the joint between FCM process and die-casting machine and formed the A380 automobile control arm parts by rheo-die-casting. The results showed that the tensile strength reached 341MPa, the yield strength was 156MPa and the elongation reached 3.6%. Liu Yong et al. studied the preparation of A380 semi-solid slurry by serpent channel, and made the parts by rheological die-casting. After T6 treatment, the maximum tensile strength was 326MPa, and the corresponding elongation was 7.03%. Fang Yuanming et al. studied the spiral electromagnetic stirring pulping and rheological die casting process of 7075 alloy. The results showed that the microstructure of the rheological die casting was fine and uniform, the average grain size was 34 μm, the composition segregation of the alloy elements (Zn,Mg,Cu) in the rheological die casting was small, and the Brinell hardness increased HB19.

Comparison of mechanical properties between semi solid forming and other processes of aluminum alloy

Table 1 summarizes the relevant mechanical properties of semi-solid formed wrought and cast aluminum alloys at home and abroad. Figure 1 shows the data in Table 1. After semi-solid rheoforming, the tensile strength and yield strength of most cast aluminum alloys are generally lower than those of metal mold casting and forging, but the elongation is generally higher than that of metal mold casting and forging. After semi-solid rheo forming, the tensile strength and yield strength of most forged aluminum alloys are generally close to the level of forgings and standard plates, but the elongation is generally lower than that of forgings and standard plates, and most of the differences are large. Therefore, the research on semi-solid forming of forged aluminum alloy has high application value. The temperature sensitivity of solid rate of 7075 and 2024 aluminum alloy is relatively low, which is suitable for semi-solid forming. Further research on semi-solid rheological forming of 7075 and 2024 aluminum alloy will improve the elongation, which will make the parts obtain good comprehensive mechanical properties. Therefore, forging aluminum alloy is the main expansion object of rheo forming application research.