Effect of Silicon Content on the Dilatometric Behavior of a Medium-Carbon Steel

Abstract

A medium-carbon steel with different silicon content was studied by dilatometric analysis during continuous heating. The critical transformation temperatures were determined from the dilatometric curves and linear regression method, applied to the dilatometric behavior and the first derivative as a function of temperature. It was observed that when increasing the silicon content, the dilatometric behavior tends to be similar as a low-carbon steel with the presence of two peaks; the first, associated with the decomposition of pearlite and the second to the austenite formation from pro-eutectoid ferrite, in the last, there was a noticeable delay in the transformation. The transformation rate was calculated employing the Johnson-Mehl-Avrami-Kolgomorov rate model and the Kissinger method was used to estimate the activation energy for each stage depending on the heating rate and the composition. Finally, a hard effect of silicon on the austenite formation was shown, especially in the second transformation stage and activation energies.