Prediction of Precipitation Sequences within Grains in 18Cr–8Ni Austenitic Steel by Using System Free Energy Method

Abstract

The applicability of theoretical energy analysis to the evolution of microstructures in heat-resistant steels was explored by using the system free energy method to predict the precipitation of M 23 C 6 and s phase within grains in 18Cr-8Ni austenitic steels. The chemical free energy of Fe-C-Cr-Ni quaternary steel and the interfacial and elastic strain energies between austenitic (g) matrix and the M 23 C 6 and s phase were estimated for the system free energy of microstructures wherein coherent or incoherent M 23 C 6 and the incoherent s phase precipitated within g grains. By identifying the minimum-energy path through a determination of system free energy hierarchies, the precipitation initiation curves of precipitates in Fe-0.07C-18.95Cr-9.57Ni steel for temperatures between 823-973 K were theoretically predicted. The calculated curves agreed well with experimental results for Type 304H austenitic steels; this suggests that the system free energy method is suitable for predicting the evolution of microstructures in heat-resistant steels.

Phase-field simulation of sensitization behavior in austenitic stainless steel weld metal with delta-ferrite existence

“…Simulation conditions and the parameters used Chemical compositions and d-ferrite volume % of the model alloys ネルギーに関しては，文献5,10,11,12) で採用されている界面エ…”