In the present study, a mathematical model has been developed to allow the prediction of the microstructural evolution and of the mechanical properties of pearlitic steel under continuous cooling in the industrial production of wire rod. By using the dilatometric technique and the metallographic method, the continuous cooling transformation (CCT) diagrams were determined for steels that are characterized by high carbon mass contents (around 0.8 %) and by alloying of 0.6 % manganese and 0.2 % silicon. Dilatometric measurements were made by using a Gleeble 3800 thermo-mechanical simulator. Two lay-heading temperatures, 900 and 780 °C, were simulated. An attempt was made to generate the CCT diagram from an experimental dilatometric curve by exploiting the Avrami equation that links the shape of the CCT curves to the value of a few parameters related to the composition of the steel. Although this approach is quite simplified, it predicted the overall behaviour of the phase diagrams with an accuracy that is sufficient to provide an initial guideline for alloy design. The strength of the pearlite was studied with hardness measurements. A connection was established between the hardness value and interlamellar spacing and the interlamellar spacing was related to undercooling. The predictive capability of the model, in terms of pearlite interlamellar spacing and strength of the rods, was tested by com-parison to measurements from an extensive plant trial.
Microstructural evolution and mechanical property correlations of 0.8 carbon wire rod
DE SANCTIS, MASSIMO;LOVICU, GIAN FRANCO;SOLINA, ADRIANO;VALENTINI, RENZO
2008-01-01
Abstract
In the present study, a mathematical model has been developed to allow the prediction of the microstructural evolution and of the mechanical properties of pearlitic steel under continuous cooling in the industrial production of wire rod. By using the dilatometric technique and the metallographic method, the continuous cooling transformation (CCT) diagrams were determined for steels that are characterized by high carbon mass contents (around 0.8 %) and by alloying of 0.6 % manganese and 0.2 % silicon. Dilatometric measurements were made by using a Gleeble 3800 thermo-mechanical simulator. Two lay-heading temperatures, 900 and 780 °C, were simulated. An attempt was made to generate the CCT diagram from an experimental dilatometric curve by exploiting the Avrami equation that links the shape of the CCT curves to the value of a few parameters related to the composition of the steel. Although this approach is quite simplified, it predicted the overall behaviour of the phase diagrams with an accuracy that is sufficient to provide an initial guideline for alloy design. The strength of the pearlite was studied with hardness measurements. A connection was established between the hardness value and interlamellar spacing and the interlamellar spacing was related to undercooling. The predictive capability of the model, in terms of pearlite interlamellar spacing and strength of the rods, was tested by com-parison to measurements from an extensive plant trial.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
