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The particle distribution in semi-solid slurry under a centrifugal field was simulated and the main factors affecting the particle distribution are discussed. The simulation results showed that a z...

Semi-solid processed high chromium cast irons were produced using a copper cooling plate and metal mould. A series of experiments were carried out to clarify the effect of heat treatment on microst...

Semi-solid metal processing of alloys is one of the key technologies for producing advanced materials. Through semi-solid processing, it is possible to produce high quality cast components from grey cast iron. A series of experiments were carried out to clarify the effect of the alloying elements copper, chromium, molybdenum, and nickel on the properties of cast iron. A comparison was made of the microstructure and mechanical properties in semi-solid processed cast iron and ordinary cast iron. This showed that an increase in the level of alloying elements in cast iron gave a higher level of hardness. However, the tensile strength of alloyed semi-solid cast iron did not exceed that of grey iron, for every composition, as a result of the characteristic microstructure produced by semi-solid processing. Thus, the alloying elements had little effect on the tensile strength of semi-solid cast iron, but did have an effect on elongation. The tensile strength of semi-solid cast iron, however, still depends on the ...

The particle distribution in semi-solid slurry under centrifugal field was simulated and the main factors such as fraction of solid, rotation speed, and holding time effecting the particle distributions are discussed. The simulation results showed that primary particles rich zone is produced in radially outer area and these results are in good agreement with the experiment. The centrifugal effect produces the primary particles distribution along the radial direction. Denser particles are concentrated in outside than inner side. For high fraction of solid samples, 'wall' appear in the middle of samples because of high viscosity region making particle difficult to move. Longer holding time gives denser primary particles concentrated more in outside than inner side. Higher rotation speed gives increased gradient of hardness in the radial direction. It is due to that number of primary austenite at inner side at higher rotation speed is less than that at lower rotation one. At higher rotation speed, ledeburite forms more at inner side of specimen than at the other one. It is also shown that semi-solid processing at lower fraction of solid gives higher hardness because smaller number of primary austenite, namely more ledeburite forms in microstructure. The present study gives useful information on producing material with locally changing property by semi-solid processing.

Local pressurization is a squeeze method for eliminating the shrinkage porosity. In this study, local pressurization was carried out with a specially designed permanent mold to examine the effect o...

This paper reports progress made in semi-solid processing of cast iron, the development of globular microstructure in various grades of iron and improvements in the mechanical properties of cast products. An explanation on the filling mechanism and flow behaviour of semi-solid slurry into a cylindrical sand mould cavity is presented based on the theory of solid feeding, interdendritic liquid flow and mass feeding. Results of analysis on fill-volume, macro- and micro-structural features are discussed for the components made by pouring the semi-solid slurry at a low solid fraction of less than 0.15 into sand moulds. In the case of the cast components, a microstructure with highly globular primary particles is observed. Precipitated graphite appears globular as opposed to the flaky structure common in castings produced under conventional methods. Vickers hardness results show hardness values higher than those of conventional castings and a decreasing pattern is observed from the edge to the centre of compone...

The stirring strength, cooling rate and solidified fraction in co-existing liquid/solid phases are important factors influencing mould filling behaviour of semi-solid metal slurry. In the present s...

In order to produce high quality castings, the various types of filtration and inoculation processes are proposed for iron casting. In this study, the double-layered ceramic foam filter system is d...

It is well known that inclusion removal processes play a key role in casting quality control and the use of ceramic foam filters has grown substantially over the past few years. In this study speci...

In order to establish the optimum cooling system for hot returned sand in metal casting processes, a mathematical model including simultaneous heat and mass transfer has been constructed. The present study is especially directed towards clarifying the dynamical behavior of sand cooling in a one-pass fluidized bed. A series of continuous cooling experiments has been made for various conditions. Characteristics of both transient and steady-state bed temperature are explained reasonably by the present model. Furthermore, a possible proposal has been given on the optimal operation, which raises heat exchange efficiency in fluidization cooling of hot molding sand.