ON MODELING AND SIMULATION OF MECHANICAL PROPERTIES OF CAST IRONS WITH DIFFERENT MORPHOLOGIES OF GRAPHITE

Castings are produced by a manufacturing method which gives the components properties that are dependant on design, metallurgy and casting method. The wall thickness influences the resulting coarseness and type of microstructure and the material will have properties dependant on local metallurgical and thermal history. The local properties in a cast iron component can vary essentially in the casting volume, which makes it difficult to optimize the castings with good accuracy. Often simulation of stress/strain of cast products use constant material properties throughout the castings. If the microstructure is determined or predicted at a given point, it is possible to calculate the local material properties and its deformation behavior. This paper presents modeling and simulation of mechanical properties related to the graphite morphology and matrix constituents, using strength and strain hardening coefficients. The mechanical properties can be shown as stress-strain curves at different locations of the cast it-on component. The models make it possible to determine qualitative stress-strain curves for any pearlitic cast iron grade and for pearlitic-ferritic ductile iron grades by knowing the graphite fraction and morphology and the chemical composition. Results from grey iron, compacted graphite irons and ductile irons are shown. These simulated local properties are validated on a complex casting in a nodular cast iron.