The Effect of Welding Process on the Chi Phase Precipitation in As-welded 317L Weld Metals

Abstract

Three multipass 317L welds were prepared using submerged arc welding (SAW), flux-cored arc welding (FCAW) and manual metal arc welding (MMA), respectively. A microstructural study was undertaken by trepanning 3 mm discs from specific positions in the weld gap, and examining the thinned specimens by transmission electron microscopy (TEM). It was found that, in addition to Chi phase precipitation detected in the regions where overlapping of the welding passes occurred, the large heat input for each welding pass can also induce Chi phase precipitation during the cooling of the welding pool. The mechanical properties showed that there were few differences resulting from the three processes. The intermetallics which formed due to high heat input passes did not appear to have a particularly harmful effect on the mechanical properties.