Abstract
In order to investigate the effect of physical properties of alloys and investments at high temperature on the casting shrinkage, the casting shrinkage of cylindric castings were measured.In addition, the physical properties of materials(the coefficient of thermal expansion, the coefficient of elasticity and yield point)were measured at high temperature;and the thermal stress and shrinkage were numerically analized.With the results of measurement, on the alloy that has no phase transformation such as Au-4.0wt% Cu alloy or α-brass, the casting shrinkage was as much as free shrinkage;but on the alloy that has phase transformation such as Au-25.0wt% Cu alloy or β-brass, the shrinkage was lessen.Furthermore the result of neumerical analysis used measured physical properties showed that the investment such as cristobalite, that expansion remains at low temperature during the cooling stage, restricts the shrinkage of alloy such as β-brass that has a low yield point at high temperature.
