Modelling and simulation of local mechanical properties of high silicon solution-strengthened ferritic compacted graphite iron

Abstract

This study focuses on the modelling and simulation of local mechanical properties of compacted graphite iron cast at different section thicknesses and three different levels of silicon, ranging from about 3.6% up to 4.6%. The relationship between tensile properties and microstructure is investigated using microstructural analysis and statistical evaluation. Models are generated using response surface methodology, which reveal that silicon level and nodularity mainly affect tensile strength and 0.2% offset yield strength, while Young′s modulus is primarily affected by nodularity. Increase in Si content improves both the yield and tensile strength, while reduces elongation to failure. Furthermore, mechanical properties enhance substantially in thinner section due to the high nodularity. The obtained models have been implemented into a casting process simulation, which enables prediction of local mechanical properties of castings with complex geometries. Very good agreement is observed between the measured and predicted microstructures and mechanical properties, particularly for thinner sections.

Keywords:

• Compacted graphite iron
• materials characterisation
• tensile properties
• solution-strengthened ferrite
• casting process simulation

Acknowledgements

The authors acknowledged the financial support of Vinnova under the FFI scheme for the project Sustainable Manufacturing of Engine components. Swerea SWECAST, Volvo Powertrain, Scania AB and SinterCast AB are greatly acknowledged for their support of this part of the project.