Program: Collaborative Research with Industry (CRI)
Field: Materials Engineering
Principal Investigator: Assoc. Prof. Dr. Nguyen Hong Hai
Sending University: Hanoi University of Science and Technology (HUST)
Japanese Co-Investigator: Prof. Dr. Keiichi ISHIHARA
Japanese University: Kyoto University
Year: 2014
Abstract:
For automobile and engine spare parts, which are important for “localization” of automobile industry in Vietnam and which are mostly made of light metals, such as aluminum and magnesium, the diecasting is the most popuparly applied method. But there are two main disvantages of diecasting: 1) formation of denderitic microstructure with many defects interdendritic and intergranular; 2) formation of pores due to turbulent character of melt flow fulfilling the mold. These disvantages can be overcome by combining diecasting with rheocasting, to generate so-called rheo-diecasting process. In this research, the rheocasting process was carried out by implementing at the same time two methodes: near-liquidus casting + cooling slop, and then diecasting to produce the components. The main results are: 1) nodular and equi-axed crystal morphology was obtained at pouring temperature to diecasting machine 650 oC, colling length 300 mm and cooling slop 45 degrees; 2) Gas porosity is decreased remarkably, expressed in the increase of specific weight from 2,62 g/cm3 to 2,67 g/cm3, approaching the ASTM standard; 3) the research results were successfully applied to produce a thick-wall component, such as pump block, which are generally very difficult to produce by diecasting process. Two research members were trained and research results were used for Ph.D thesis student Knowledge on rheodiecasting technology for reseach members and students were increased. By applying this technology the highquality castings can be made, which increase the percentage of spare parts that we can produce ourself, hence decrease the amount of imported ones.