Abstract
In recent studies grain boundary segregation isotherms determined through fracture experiments in a scanning Auger microprobe have been employed to analyse the influence of tensile stress on grain boundary segregation at 773 K. The present study examines in greater detail the effect of stress on the grain boundary segregation behaviour of 2·6 wt-%Ni–Cr–Mo–V steel in the heat treatment temperature range ∼770–900 K. A comparison of grain boundary segregation isotherms recorded for the isothermally heat treated low alloy steel under stressed and unstressed conditions suggests that the application of tensile stress results in an increase of the segregation rate and concentration of grain boundary segregating elements N, P, and S. The enhancement in the grain boundary coverage as a result of stress was more marked for S and the activation energy for the diffusion of S under tensile loading conditions was measured to be ∼106·3 kJ mol−1. Of the various interaction processes (Cr–N, Cr–P, P–S), site competitive P–S interaction is particularly activated on application of the tensile stress in the temperature range ∼770–850 K. However, the influence of temperature on segregation is independent of the applied tensile stress for any of the stress affected interaction processes.
MST/1703
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