Effect of the cooling rate on the tensile strength of pearlitic lamellar graphite cast iron

ABSTRACT The effects of cooling rate and carbon equivalent on the tensile strength of pearlitic lamellar graphite cast irons were investigated. The cooling rate was varied from 6°C/s to 35°C/s for values of the carbon equivalent equal to 4.17% and 3.83%. The increase in the cooling rate promoted the refining of the eutectic cell size, primary dendrite modulus, interdendritic hydraulic diameter and pearlite interlamellar spacing. The increase in the cooling rate also refined their graphite flakes, changing the morphology from B to E type. The reduction in the carbon equivalent increased the proportion of primary dendrites from 25% to 40%. The maximum tensile strength increased from 274 to 524 MPa with the increase in the cooling rate and the reduction in the carbon equivalent. These results were used to test two tensile strength predictive models based on modified versions of the Griffith and Hall-Petch equations.