Preparation and Rheo-Die Casting of Semi-Solid A356 Aluminum Alloy Slurry through a Serpentine Pouring Channel

2012 ◽  
Vol 192-193 ◽  
pp. 404-409 ◽  
Author(s):  
W.M. Mao ◽  
Z.Z. Chen ◽  
H.W. Liu ◽  
Y.G. Li

The semi-solid slurry of A356 aluminum alloy was prepared through a serpentine pouring channel, which is a new method proposed recently for semi-solid forming process, and the effect of pouring temperature and bend number in the channel on the slurry microstructure was investigated and the slurry was finally rheo-die cast. The results show that when the pouring temperatures are between 640oC and 680oC, the slurry of A356 aluminum alloy with spherical primary a-Al grains can be prepared under the given conditions. The more the bend numbers in the channel are, the better the slurry is, i.e. the primary a-Al grains are more spherical and finer. The results also show that the as-cast ultimate strength and elongation of the rheo-die castings can reach 250MPa and 8.613.2% respectively. After T6 heat treatment, the ultimate strength and elongation of the rheo-die castings can reach 320MPa and 8.011.3% respectively. The work undertaken demonstrates eventually that the serpentine pouring channel process is a good method for semi-solid rheo-die casting or rheo-forming of metallic materials, the process is simple and the slurry cost is not expensive.

2006 ◽  
Vol 116-117 ◽  
pp. 453-456 ◽  
Author(s):  
Yong Lin Kang ◽  
Yue Xu ◽  
Zhao Hui Wang

In this paper, with a newly self-developed rotating barrel rheomoulding machine(RBRM), microstructures and mechanical properties of rheo-die casting A356 alloy were studied. In order to clearly show the characteristic of rheo-die casting, liquid die casting and semi-solid casting were done too. The experimental results showed that microstructures of rheo-die casting were composed of solid grains, which were finer and rounder, and had fewer pores. In the three technologies, integrated mechanical properties of semi-solid rheo-die casting were the best.


2016 ◽  
Vol 877 ◽  
pp. 39-44
Author(s):  
Si Min Lei ◽  
Li Gao ◽  
Yohei Harada ◽  
Shinji Kumai

The present work deals with the relationship between microstructure and mechanical properties of A356 aluminum alloy which was produced via thixocasting process under different casting conditions. Feedstock billets were heated to a target temperature to obtain a semi-solid slurry with the required solid fraction. Some billets were heated to a fully-melted condition. In order to obtain fine and spheroidized Al grains, some billets for the partially melting were compressed axially by 33% at a room temperature before heating. The completely-melted and partially-melted slurries were die-cast by using a die-cast machine, and hour glass-shaped rod-type tensile specimens and small-size plate-type tensile specimens were obtained. Small cubic specimens were also collected from the die-cast products for microstructural evaluation. They were polished, and etched by Weck’s reagent. The partially-melted specimen which was compressed before heating shows the spherical Al grains. But the grain of the strain-free partially-melted specimen exhibited complicated morphology. The fully-melted specimen shows the fine and dendrite structure.


2010 ◽  
Vol 97-101 ◽  
pp. 306-310 ◽  
Author(s):  
Xiang Lin Yin ◽  
Yi Tao Yang ◽  
Yu Peng Shao ◽  
Guang Jie Shao

The non-dendritic of A356 aluminum alloy billet was reheated to meet the requirements of the semi-solid microstructure by three different kinds of power, achieving the same final temperature of 863K. Subsequently, under the same conditions of die-casting (thixoforming), the microstructure was observed, surface hardness and tensile properties were measured. Afterwards, quantitative analysis was made for the microstructure of the reheated semi-solid of billet and the thixoforming parts. The results showed that the larger induction reheating power of the billet, the smaller the grain size of its microstructure and the higher surface hardness and the better mechanical properties of its thixoforming sample. Finally, through studying on the relationship between the microstructure of the semi-solid billet of A356 aluminum alloy and the mechanical properties of the thixoforming sample, we primarily achieved the reverse design of microstructure.


Author(s):  
Heng Hua Zhang ◽  
Xian Nian Zhang ◽  
Guang Jie Shao ◽  
Luo Ping Xu ◽  
Yi Tao Yang ◽  
...  

2014 ◽  
Vol 217-218 ◽  
pp. 241-246
Author(s):  
Yue Long Bai ◽  
Jun Xu ◽  
Zhi Feng Zhang

The effects of annulus gap width, stirring power and stirring frequency on the microstructure of the semi-solid A356 aluminum alloy slurry have been investigated by the annulus electromagnetic stirring (AEMS) technology The results show that narrow annulus gap , strong stirring power and high stirring frequency are advantageous to obtain the small spherical primarymicrostructure, the smaller the annulus gap width is, the bigger the stirring power is, and the higher the stirring frequency is, the more uniform, the smaller and the more spherical the microstructure is. So the high stirring frequency, narrow annulus gap, strong stirring power are beneficial to obtain the fine and spherical semisolid microstructure in AEMS. Also the results indicate that the primary particles are globular, small and distribute homogeneously in the AEMS.


2014 ◽  
Vol 794-796 ◽  
pp. 9-14
Author(s):  
Li Gao ◽  
Yohei Harada ◽  
Shinji Kumai

An A356 aluminum alloy billet which has a dendritic microstructure was compressed and then partially re-melted to semi-solid state before water quenching, by which the spheroidization of Al grains was realized. A color etchant called Weck's reagent was used to characterize both the dendritic and spheroidal microstructure. In both cases, distinct color differences were observed inside Al grains by normal optical microscopy. Interestingly, a dendritic-shaped structure inside the spheroidal Al grains was visualized, which should be the reflection of the original dendrite before heating and partial re-melting. Also, the grain growth during water quenching could be clearly visualized after etching with this reagent. As a result, solid fractions could be evaluated more precisely by excluding the grain growth when measuring the area of solid phase in 2-D micrographs. In order to investigate the coloring mechanism, electron probe micro-analyses were carried out to characterize the micro-segregations inside an Al grain. Results showed that the micro-segregation of Ti had a strong correlation with the color difference. Detailed investigation found that the micro-segregation of Ti could be preserved after heating and partial re-melting due to the extremely low diffusion rate of Ti in Al.


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