Effect of vanadium on grain boundary segregation of phosphorus in low alloy steels

The phosphorus grain boundary segregation at 853 K was investigated in thre e low alloy steels with different vanadium content. Kinetic dependence of t he phosphorus grain boundary concentration was determined experimentally by means of AES and described theoretically, as well. To assess the influence of the individual alloying elements on the phosphorus segregation, the met al composition of carbide phases at 853 K was predicted by means of thermod ynamic calculations and confirmed by experimental measurements (TEM + EDX). The vanadium was found to enhance the phosphorus grain boundary segregatio n by reducing the amount of dissolved and segregated carbon. Thereby, the e quilibrium of mutual displacement C (segregated) double left right arrow P (segregated) was shifted to more phosphorus segregation. The results achiev ed indicate that vanadium indirectly increases sensitivity of tow alloy ste els to intergranular embrittlement.