Preparation Process and Optimization of High-Strength Cylinder Head Made from RuT500 Compacted Graphite Iron

Compacted graphite cast iron (CGI) possesses excellent mechanical properties and is widely used in manufacturing cylinder blocks and heads for high-power internal combustion engines. However, higher tensile strength in CGI corresponds to a greater probability of shrinkage porosity defects occurring during production, resulting in few manufacturers being able to stably produce cylinder heads made of the RuT500 high-strength material grade. To address the shrinkage porosity issue in RuT500 high-strength cylinder heads, this study conducted experimental research focusing on raw material selection and control, the influence of carbon equivalent (CE) on tensile strength and shrinkage porosity, and the optimization of casting feeding design. The results indicate that, based on the specific structural characteristics of this cylinder head and the casting process conditions, cylinder heads with a body tensile strength exceeding 500 MPa and free from shrinkage porosity defects can be successfully produced by selecting high-purity or ultra-high-purity pig iron as the raw material when CE ≤ 4.43 and the riser feeding modulus is 2.2.