KINETICS OF PHOSPHORUS SEGREGATION IN 2.7CR-0.7MO-0.3V STEELS WITH DIFFERENT PHOSPHORUS CONTENTS

The phosphorus grain boundary segregation kinetics during tempering at 680 degrees C and aging at 500 degrees C of 2.7Cr-0.7Mo-0.3V steels w ith phosphorus mass contents of 0.004, 0.014, and 0.027% was investiga ted. To determine the grain boundary concentrations of phosphorus the Auger electron spectroscopy was used. Chemical compositions of carbide particles were determined by means of EDX/STEM. Xu Tingdong's and Mcl ean's models of non-equilibrium and equilibrium segregations, respecti vely, were used to analyze experimental data. It was shown that a phos phorus grain boundary enrichment during tempering was mainly caused by non-equilibrium segregation. During aging the mechanism of the equili brium grain boundary segregation was prevalent. Slow phosphorus segreg ation kinetics was observed in the experimental steels during aging.