Effect of the casting thickness (3.2 to 5.8 mm) on the tensile strength of grey cast iron

The tensile strength and the macro and microstructures of pearlitic grey cast iron with wall thickness varying from 3.2 to 5.8 mm (cooling velocity between 29 e 6°C/s) were investigated. Microscopic characterization techniques were employed to quantify the main macro and microstructural parameters. The reduction in cast thickness refined the austenite dendrite arm spacing (SDAS), the mean size of the eutectic cell (TMCE), the mean size of the pearlite colonies (TMCP), the pearlitic interlamellar spacing (λ_pearlita) and the interdendritic hydraulic diameter (D_Hid). Consequently, there was an increase in the average value of the tensile strength from 274 to 420 MPa due to the increase of the cooling velocity. These results were used to test two mathematical models, which use the macro and microstructural parameters of the pearlitic grey cast irons to predict their tensile strength. (author)