Second Phase Precipitation in As-Welded and Solution Annealed Alloy 22 Welds

The precipitation characteristics of tetrahedrally close-packed (TCP) phases during the welding and the subsequent solution annealing process of Alloy 22 1 1/2” thick plate double-U prototypical welds are investigated. Electron backscatter diffraction (EBSD) was used to provide large scale microstructural observation of the weld cross section, and scanning electron microscopy (SEM) was used to map the location of the TCP phases. Analysis shows that TCP precipitation occurs congruent to the weld passes, with the solution annealing reducing the sizes of coarser precipitates.