Tracking changes in segregation on a single grain boundary in a ferritic steel by repeated atom probe tomography

Atom probe tomography is widely used for measuring grain boundary segregation. However, its destructive nature and the time intensive sample preparation process make it challenging to compare different material states with statistical significance, especially considering that segregation behavior depends on grain boundary character. This study introduces a methodology enabling multiple atom probe tomography measurements on a single grain boundary after successive heat treatments. This approach allows the temporal evolution of segregation to be traced under varying annealing conditions. Using this method, we identified distinct segregation tendencies for alloying and tramp elements in a titanium stabilized interstitial free ferritic steel.
Our results revealed that the competitive mechanism between segregation and precipitation reduces Ti and C segregation at lower temperatures. Conversely, Sn, Sb, and P exhibited increased segregation after prolonged annealing at 660 °C, likely contributing to intergranular embrittlement. This proposed methodology provides new opportunities to analyze the segregation behavior of tramp and trace elements in steels.