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.

Study of the Effect of Multiple Tempering on the Impact Toughness of Forged S690 Structural Steel

“…Increasing tempering time leads to evolution of the unstable carbides towards the equilibrium ones, whose nature depends on the steel composition. This event is usually accompanied by coarsening and spheroidization of carbides [21].…”

Additive manufacturing of carbon-martensitic hardening ledeburitic cold work tool steels using Fused Filament Fabrication and subsequent Supersolidus Liquid-Phase Sintering

“…During the solid-state sintering process, the metal cells undergo a slight Ostwald ripening, and the morphology of the Cr-rich carbides is transformed from network-like to spherical, with a diameter of 1 to 4 µm. The effective driving force for the spheroidization of the eutectic carbides with previous herringbone morphology is the reduction of the interfacial energy between orthorhombic M 7 C 3 and fcc metal matrix, considering the strain energy and the associated misfit stresses [61]. However, the carbides counteract the pronounced Ostwald ripening of the metal cells during solid-state sintering so that a fine microstructure is retained.…”

High-Strength Low-Alloy Steels

“…Xie et al [3] studied the effect of nanometre-sized interphase-precipitated carbides on the improvement of monotonic tensile strength in fire resistant hot-rolled steel at room and high temperature. The effect of dissolution and precipitation of different carbides at high temperature on the microstructure of a low-alloy chromium-containing heat-resistant steel was also analysed by Li et al [4].…”