Investigation of solute segregation behavior using a correlative EBSD/TKD/APT methodology in a 16MND5 weld

In the present study, a correlative Electron Backscattering Diffraction (EBSD)/Transmission Kikuchi Diffraction (TKD)/Atom Probe Tomography (APT) methodology was used to investigate the solute segregation behavior in a low-alloyed weld. Three dimensional chemical information was correlated to the crystallographic features of Grain Boundaries (GBs). The steel has a complex microstructure of acicular ferrite and intergranular carbides. About 78% High Angle Grain Boundaries (HAGBs, with about 12% Sigma 3 HAGBs) and about 22% Low Angle Grain Boundaries (LAGBs) were observed. APT analyses revealed the segregation of one element or several chemical species (C, P, Mn, Si, Ni, Cr and Mo) at GBs or carbide-ferrite interfaces. Taking into account the nature of segregants and the five-parameter GB crystallography, both interstitial and substitutional segregation behaviors were discussed. The results reveal a significant influence of misorientation angle (or deviation angle) on interstitial segregation for LAGBs (or Sigma 3 special HAGBs) and also a strong influence of the GB plane on substitutional segregation for Sigma 3 special HAGBs and general HAGBs. (C) 2019 Elsevier B.V. All rights reserved.