Segregation and precipitation at grain boundaries of weathering steels without/with Sb addition

Grain boundaries (GBs) are important microstructural features in steels. The segregation and precipitation at the GBs are of significance in determining the performance of the steels in service. This research carefully selected a low-angle GB and three high-angle GBs with similar misorientation angles to perform atom probe tomography (APT) investigation. Our advanced APT analysis is successful in accessing comprehensive crystal orientation and chemical information of neighbour grains in the two weathering steels, and gains new insights into the segregation and precipitation at the GBs. The high-angle GBs exhibits very different segregation characteristics from the low-angle GB. Sb strongly partitions only into a Cu-rich precipitates, rather than carbides in the Sb-containing steel. The strong interaction between Sb and Cu is responsible for the unique segregation of Cu at GB. Major factors governing GB segregation have been comprehensively addressed in this investigation.