Crack sensitivity of circumferential weld structure for superalloy GH2132

The TIG welding process tests of the circumferential weld between the bearing disk and the stud made of superalloy GH2132 with different boron content were carried out. The crack rates in the weld on the surface and cross-section of the weld were measured. The mechanism of weld crack was analyzed based on the microstructure and XRD measured residual stresses. The results shown that welding crack sensitivity exists in TIG welded joints of GH2132 alloy. The cracks appear in the coarse grain zone near the fusion line of the weld, and spread to the base metal along the grain boundary, which belong to liquation crack. The crack sensitivity rises with the increase of the heat input. The content of boron in the alloy has a significant influence on the sensitivity of the liquation cracking. The higher the boron content in the alloy, the higher the crack sensitivity. The location of the crack in the circumferential weld is related to the structural characteristics of the component. If the disk has a circular hole in its center and the stud on the plane of the disk is close to the hole, the crack appears in the outer side of the circumferential weld of the stud, due to the fact that the stress of the weld outside of stud is higher than that in the weld inside of the stud during welding.