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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 me...

A model for the yield strength of artificially aged Al–Si–Mg casting alloys has been developed. The model includes Mg concentrations between 0.2 and 0.6 wt-% and aging temperatures between 150°C an ...

Primary austenite is the least investigated microstructural component of grey cast iron. It is the first phase to be nucleated in the liquid metal and it grows in a dendritic manner, followed by growth of the eutectic phase. This paper describes an investigation on three potential nucleating agents to promote the nucleation of primary austenite in grey cast iron under industrial conditions. A direct austempering after solidification (DAAS technique) was used to determine the number of primary austenite grains. A colour etching technique was used to reveal the primary austenite grains and the eutectic cells. The results show that properly chosen nucleation agents significantly promote the number of primary austenite grains. Furthermore, the authors show that the eutectic cell size and the morphology of the graphite are obviously influenced by the primary solidification in grey cast iron. The increased nucleation of austenite grains resulted in an increased number of eutectic cells.

The thermal transport properties of five predominately pearlitic grades of grey, compacted graphite and spheroidal graphite iron have been investigated by the laser flash technique. Samples have been taken from cylinders cast in controlled thermal environments designed to produce three dissimilar cooling rates. Digital image analysis has been utilised in order to characterise the different graphite morphologies. The results indicated linear relationships between the thermal transport properties and the roundness of the graphite and the nodularity for compacted graphite and spheroidal graphite iron. A pronounced decrease in the thermal conductivity occurred when the lamellar graphite structure was transformed into compacted graphite. The thermal conductivity of compacted and spheroidal graphite iron has been recalculated with good accuracy over a temperature range of 25–500°C by means of regression analysis.

Effects of transition from lamellar to compacted graphite on thermal conductivity of cast iron

The thermal conductivity of grey iron cast with different solidification conditions and treated with different inoculants has been evaluated by the laser flash technique. Colour etching has been utilized to reveal the influence of the fraction of primary phase and the eutectic cell diameter. The thermal conditions during solidification together with inoculation largely affect the heat conductivity of grey iron. The results show that an increased fraction of primary austenite depresses the thermal conductivity, while straight, long graphite flakes of type A are favourable with regard to the ability to transfer heat.

The deformation of metallic materials includes both an elastic and a plastic deformation. In the case of cast irons, the elastic region becomes less pronounced as the graphite changes from ...

Deterministic modelling is a classical method used for solidification simulation. A common procedure uses a kinetic model to describe the growth of solid phases. Formulation of the kinetic models u ...

Nine grades of pearlitic cast iron containing different graphite morphologies (from flake, compacted and spheroidal) have been studied. The parameters investigated include the graphite aspect ratio, nodularity, graphite size and modulus of elasticity. These parameters have been correlated and compared with different existing bound and model equations. It has been found that the modulus of elasticity of the graphite phase increases as the aspect ratio and nodularity of the graphite increases, i.e.flake graphite gives a lower modulus of elasticity than spheroidal graphite. The experimental values of the modulus of elasticity show good agreement to bound and model equations, although flake graphite cast irons show higher deviation from the modelled values. An equation for the correlation between the graphite modulus of elasticity and the nodularity is presented. Introducing this linear correlation into an existing model for the determination of the effective modulus of elasticity gives a continuous f...

Comparison of Mechanical Properties in Flake Graphite and Compacted Graphite Cast Irons for Piston Rings

Influence of Antimony on Microstructure Formation and Mechanical Properties in Thick-walled Ductile Iron Castings

The interest to improve the mechanical properties and decrease shrinkage or expansion defects in grey cast irons, the inoculation is an important issue for component manufactures. The inoculation, ...

A comparative study of the mechanical properties of 20 experimental alloys has been carried out. The effect of different contents of Si, Cu, Mg, Fe and Mn, as well as solidification rate, has been assessed using a strength-ductility chart and a quality index-strength chart developed for the alloys.The charts show that the strength generally increases and the ductility decreases with an increasing content of Cu and Mg. Increased Fe (at Fe/Mn ratio 0.5) dramatically lowers the ductility and strength of low Si alloys. Increased Si content generally increases the strength and the ductility. The increase in ductility with increased Si is particularly significant when the Fe content is high. The charts are used to show that the cracking of second phase particles imposes a limit to the maximum achievable strength by limiting the ductility of strong alloys. The (Cu + Mg) content (at.%), which determines the precipitation strengthening and the volume fraction of Cu-rich and Mg-rich intermetallics, can be used to s...

Nineteen compacted graphite cast irons were investigated in order to determine how alloying additions affect the thermal transport properties and microstructure. All melts were based on one chemica ...

An investigation of the effect of inoculants on the metal expansion penetration in grey iron