Dilatometric Analysis of the Martensite Decomposition by Stages During Continuous Heating

Abstract

The martensite decomposition by stages was studied in an experimental medium-carbon steel alloyed with vanadium under conditions of continuous heating and differential dilatometry. For the dilatometric analysis, cylindrical specimens of 5 mm diameter and 15 mm length were machined and heated at different rates: 0.58, 0.75 and 0.91 °C s−1 until reaching a temperature of 1000 °C, then the specimens were cooled to room temperature. Through the dilatometric analysis and the strain rate by dilation, the critical points corresponding to the martensite decomposition stages were determined, and the energies of activation by stages were calculated employing the Kissinger method. Lastly, five critical points associated with stages of dissolution, precipitation and phase transformation were identified, as well as observing that the critical points displacement to higher temperatures as the heating rate increases while the values of the activation energies were agreed to values reported for different stages of martensite decomposition.