Optimization of mechanical properties of high-stressed castings with direct checking of casting process

摘要

The microstructural properties of castings with a complex geometry, as well as their corresponding mechanical properties may vary considerably from one place to another due to locally varying cooling and solidification conditions of the heat. As an example of an automobile cylinder head segment made of the alloy AlSi7Mg0.3 (A356) has shown, the secondary dendrite arm spacing (DAS) of the as-cast structure and, based on this, the field of mechanical properties (i.e. tensile strength R_m 0.2 percent yield strength R_(p0.2), elongation to fracture A and quality index Q) can be determined by computer-assisted simulation of the change of the temperature field over time as a function of the local solidification time t_s. This makes it possible to forecast and control any changes in the casting's strength properties caused by particular casting techniques used. In addition, the field of internal stresses can be calculated and related to the strength properties.