The dissolution of cementite in a low carbon steel during isothermal annealing at 700°C

Abstract

An experimental and theoretical investigation of the dissolution of cementite in ferrite at 700 °C has been performed. Special attention has been paid to the variation of the matrix carbon content with annealing time and prior heat treatments. A fine structure of spherical cementite particles yields a more rapid increase in carbon dissolved at short times whereas a coarse structure of grain boundary cementite yields a more rapid increase at rather long times. A lower temperature annealing extended over several hundred hours yields a Mn enrichment in the cementite and displaces the subsequent dissolution at 700 °C toward longer times. The effect is not so pronounced in the case of the coarse structure due to a lower degree of enrichment.