Carbide Precipitation, Dissolution, and Coarsening in G18CrMo2–6 Steel

Abstract

The precipitation, dissolution, and coarsening of different carbides at 680 °C in G18CrMo2–6 steel was investigated experimentally combined with Jmatpro simulation. The G18CrMo2–6 steel was normalized at 940 °C, followed by tempering at different times at a constant temperature of 680 °C. During the tempering process, there are mainly two kinds of carbide, namely M3C and M23C6. Through characterization of microstructural evolution, thermodynamic calculation, and kinetic simulation, it was observed that during the tempering process, the stable M23C6 carbide was growing, whereas the metastable M3C carbide was disappearing. At the end, the M3C carbide was dissolved and the M23C6 carbide was in equilibrium with the matrix.