Microstructural aspects of phosphorus grain boundary segregation in low alloy steels

The influence of microstructure on phosphorus grain boundary segregation in 2.6Cr–1Mo–0.3V low alloy steel was investigated. Measurement of the phosphorus grain boundary concentration and characterization of the steel microstructure (substructure) were performed by means of Auger electron spectroscopy (AES) and transmission electron microscopy (TEM). It was found that the phosphorus grain boundary segregation during the aging of the steel at 773 K is faster in as-tempered microstructure than in as-quenched material. The lower dislocation density and the indirectly evidenced lower carbon content in ferrite matrix were considered to accelerate the kinetics of phosphorus segregation.