DEVELOPMENT OF PREDICTIVE PROCEDURES FOR EVOLUTION OF METASTABLE MICROSTRUCTURES IN 9CR-1MO STEELS

The present paper presents a new concept of Phase Evolution Diagram ba sed on analytical electron microscopy for 9Cr-1Mo steel in the tempera ture range of 823-1023K. The Phase Evolution Diagram has been construc ted based on the variation of the solute concentration of unprecipitat ed ferrite with time. The different metastable phase fields which evol ve as a consequence of this variation are also superimposed in the dia gram. The paper demonstrates the usefulness of the FED in assessing th e previous thermal history and predicting the subsequent microstructur e states for 9Cr-1Mo steel, based only on the knowledge of the composi tion of the parent matrix.