MODELING AND SIMULATION OF ELASTIC PROPERTIES IN CAST COMPACTED GRAPHITE IRON ENGINE BLOCKS

摘要

This paper aims to demonstrate the capabilities of microstructure modeling in compacted graphite cast iron castings for stress and strain optimization using state of the art knowledge. The elastic properties vary in the casting material depending on the volume of graphite, shape of graphite and nodule count. The simulation of microstructure also takes into account the inoculation, solidification of compacted graphite eutectic and nodular growth. The microstructure of compacted graphite cast iron is strongly affected by the casting conditions where the resulting nodularity to a great extent depends on solidification rate and metallurgical treatment.rnIn the engine components of today it is seen that the thermal strains are increasing due to an increase in top pressures. This results in higher stresses within the components and thus the demands on the engine material increases. Due to these demands, compacted graphite cast irons are found to be a viable choice of cast iron material for engine components. In a recent study a series of experiments containing five grades of compacted graphite cast iron with different nodularities were cast. From these grades, the modulus of elasticity was determined and correlations to microstructural parameters were established. By using a two-phase model, together with the found correlations, for the modeling of the elastic properties in different grades of cast iron, a very good prediction power was achieved.rnThe model has been implemented in a casting simulation software, to simulate the resulting elastic properties in a compacted graphite cast iron casting. The dependence on casting conditions and location in the casting, inoculation, metallurgical treatment, microstructure and elastic properties are presented in this paper. A comparative study of simulated and experimental values of the elastic properties of an engine block is also shown.