A high-resolution Auger electron spectroscopy study of the intergranular fracture of a temper-embrittled steel

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Abstract
One of the earliest uses of Auger electron spectroscopy was the analysis of the intergranular fractures to determine how segregated impurities produce intergranular embrittlement. As spatial resolution improved it became evident that the impurities were inhomogeneously distributed among individual intergranular facets. Further improvement in the spatial resolution now with primary beam diameter down to 0.1 μm has revealed that impurity distribution even on individual intergranular facet can be highly nonuniform. In this study we report on a CrMoV steel steam turbine rotor embrittled by P segregation during 20 years of service revealing that the grain boundaries were mainly covered by two kinds of carbides: one Cr rich and the other Mo rich. The P level at the Cr rich carbides was generally lower than on the carbide-free regions.