Study on the Distribution Characteristics of Microstructure and Mechanical Properties Within the Cylinder Head of Low-Pressure Sand Cast Aluminum Alloy

The cylinder head is one of the most complex and concentrated load components of the engine, playing an important role in the safety and reliability of the engine. In this paper, the finite element method is used to simulate the casting and heat treatment process of cylinder head. The distribution characteristics of microstructure, shrinkage porosity defects as well as mechanical properties are analyzed, and the mechanical properties simulation results were verified by experimental data. The results show that the microstructure varies significantly at different regions and is related to local cooling rate. The shrinkage porosity defects are mainly distributed in the thick walls and thin–thick wall junctions, but the porosity value is small and the effect on the mechanical properties could be ignored. The mechanical properties of different cylinders are similar, but there are obvious differences at the top plate, force wall and bottom plate in each cylinder, with a maximum difference of 12%. The large discrepancies of microstructure, shrinkage porosity defects as well as mechanical properties in cylinder head are caused by the different local filling and cooling conditions in the casting process.