Ultrasound is defined in terms of human hearing and it is a sound having a frequency higher than that to which the human ear can respond. The attempts to use the ultrasound at casting process have been carried out and there are a lot of study results on grain refinement on microstructure of casting alloys. However, these studies almost have been focused on mould vibration at solidifying melts of solid and liquid coexistence temperature. In this study, high intensity ultrasound was injected in aluminium full melts, especially A390 alloy, to evaluate the effect of ultrasound on microstructure and mechanical properties of castings. The effect of ultrasonic injection on melts could be summarised as follows: reduction of mean size of primary silicon, variation of phase distribution, improvement of solute homogeneity and mechanical properties.
Castability, in a narrow sense, means the formability of a particular liquid metal into a desired shape by transformation from liquid to solid. Considering the importance of recycling, the reuse of returned scrap should be related to castability. In addition, glass forming ability should also be studied for bulk amorphous metals, as it is very closely related to crack formation during casting. This paper reports a study on the castability of Cu-base bulk amorphous alloy made by conventional vacuum induction melting. The effects of specimen thickness, number of remeltings, and mold temperature were investigated. A test mold for thin plate specimens was designed in order to evaluate the liquid formability of the alloy. Mold filling was good for 2 mm specimens; however, many cracks were observed after cooling. While the mold cavities were not fully filled for 1 mm specimens, no cracks could be found. The glass forming ability also became worse with increasing number of remeltings; this worsening is believed to be caused by the increase in oxygen content.
Chill vent has a zigzag venting path which allows residual air or gases to exhaust out very quickly from the die cavity. However molten metal sometimes comes out through the gas venting surfaces causing flash. Effect of designing factors of chill vent and processing variables in high pressure die casting on the performance of chill vent was investigated through a series of calculations by using a commercial code. The most influential factor was the thickness of chill vent, followed by inlet velocity, vent width and die temperature.Key words: High pressure die casting, Performance of chill vent, Fill ratio.
To add alloying elements into a pure copper melt, the wire-feeding efficiency of cored (alloy containing) wire was evaluated using a commercial, computational fluid-dynamics program. The model design was based on an industrial-scale production line. The variables calculated included wire feed rate, melt temperature, wire diameter, melt flow rate and wire temperature. Efficiency was evaluated after a series of calculations based on the penetration depth of the alloy-wire into the molten copper bath. Of the five variables investigated, the wire feed rate and wire diameter were the most influential factors affecting the feeding efficiency of the cored-wire.
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