Austenitization kinetics of pearlite and ferrite aggregates in a low carbon steel containing 0.15 wt pct C

Abstract

Austenitization kinetics of pearlite and ferrite aggregates, in a low carbon steel containing 0.15 wt pct C. were studied in the temperature range of 800 to 870 °C. The transformation was monitored by estimating the volume fraction of austenite and the surface area per unit volume of the austenite-ferrite interfaces by quantitative microscopy. It is concluded that the austenite growth geometry is two dimensional. Between 800 and 840 °C, the two dimensional radial growth of the austenite particles can be described by a simple parabolic law. This suggests a diffusion controlled growth mechanism. However, at 870 °C, the kinetics of the process are different from those at the lower temperatures studied, and the radial growth rate approaches a constant value at long times.