Abstract: Based on the theory of grain boundary segregation, a kinetics model of temper embrittlement caused by long-term service for hot-wall hydrofining reactors was studied. The kinetics model was applied to phosphorus (P) segregation in 2.25Cr-1Mo steel used for a hot-wall hydrofining reactor, and the kinetics of grain boundary segregation of impurity P in the steel exposed to the process environment of the hydrofining reactor was calculated on the basis of the model. The Auger electron spectroscopy test was performed in order to determine the grain boundary concentration of P. The experimental result is agreement with the theoretical calculated data. The results show that the kinetics equation is reasonable for predicting the levels of grain boundary segregation of impurity P in 2.25Cr-1Mo steel used for hot-wall hydrofining reactors.

Key words: hydrofining reactor, 2.25Cr-1Mo steel, temper embrittlement,