Phosphorus grain boundary segregation under different applied tensile stress levels in a Cr-Mo low alloy steel

Phosphorus grain boundary segregation during 100 MPa stress ageing at 520 °C in a 2.25Cr1Mo steel is observed using Auger electron spectroscopy. In the segregation kinetics there is only a depletion trough of phosphorus below its thermal equilibrium level. Combined with preceding experimental results for other stress levels, the evolution of segregation kinetics with stress is addressed. The basic features of the segregation kinetics include two segregation peaks and one depletion trough. The first peak, the second peak and the trough may be related to the vacancy-solute complex effect, the boundary diffusion effect and the creep deformation inhomogeneity effect, respectively.