Nano-size Particle Evolution During Heat Treatment of P91 Steel and Their Effect on Micro Hardness

Abstract

In the present research work, creep strength enhanced ferritic/martensitic P91 steel was subjected to varying normalizing (950�1150 �C) and tempering temperature (730�800 �C). The varying normalizing and tempering temperature effect on microstructure evolution (precipitate size and their distribution and grain size) and microhardness were performed. The heat treatment consequences on microstructure evolution revealed an increase in grain size, and decrease in fraction area of precipitates, with increase in normalizing temperature. The grain size was found to be decreased with increase in tempering temperature while fraction area of precipitates and precipitate diameter increased. For microstructure characterization, optical microscope and field emission scanning electron microscope were utilized. The microhardness was found to be increased with increase in normalizing temperature while it decreased with increase in tempering temperature. � 2017 The Indian Institute of Metals - IIM