The effects of out-of-mold chills on solidification characteristics in a plate-shaped pure aluminum casting with pin-fins were numerically examined by heat transfer and solidification simulation, and concepts for the casting designs of the baseplate integrated with fins made by directional solidification method using chills and high temperature molds were also investigated. The numerical results showed that both greater end effects and shorter solidification time can be obtained by the synergistic effect of high temperature molds and out-of-mold chills. Meanwhile, it was found that the solidification time tends to have a linear relationship with casting volumes, and that liquid isolation in the pin-fins occurs under longer solidification times. Here, it is thought that the conditions generating the liquid isolation in the pin-fins may be unsuitable for manufacturing by casting. In addition, it was suggested that the plot of the heat-exchanging performance versus solidification time may be useful for the casting design of the baseplate integrated with fins. Furthermore, it was shown that the liquid isolation can be prevented by placing an out-of-mold chill on the pin-fin-side surface.

  In order to investigate the flow of molten metal in the cavity of a die, experimental simulation was carried out using a water flow model. The experimental cavity has a backward step configuration at the test zone, where the flow behavior and air exhaust process were investigated. The rib material was installed at the step to study its effects on air exhaust for various Reynolds numbers (flow velocities) and rib installation conditions. The main results obtained are as follows. The flow behavior in the cavity with rib can be classified into two patterns. This classification is mainly influenced by the thickness of the rib, and hardly influenced by the Reynolds number (flow velocities) and rib position. The best conditions for the rib thickness and position achieved air exhaust in a short time with little air remaining inside. Increasing the Reynolds number (flow velocities) is effective for suppressing casting defects due to the entrainment of air.

  In order to predict residual stress in castings, elasto-plastic models are used in thermal stress analysis, however conventional elasto-plastic models cannot express the recovery of the casting during cooling.

  In this study, thermal stress analysis of JIS ADC12 alloy castings was conducted using an original elasto-plastic-creep model developed by the authors, and the calculation results were validated with the experimentally obtained thermal stress. The model takes the recovery into account, which is a characteristic behavior of alloys at high temperatures. For the validation, an original device was also developed to measure the thermal stress in JIS ADC12 alloy cast specimens during cooling. The simulated thermal stress was continuously compared with the measured thermal stress. As a result, it was found that compared to the elasto-plastic model, the developed elasto-plastic-creep model is able to more accurately predict not only the thermal stress during cooling but also the residual stress.