Mechanical Properties and Fracture Characteristics of Welded Joint in GH536 Ni-based Superalloy

Microhardness, tensile properties and fracture toughness of based metal and different zones in welded joint for GH536 obtained by gas tungsten arc welding (GTAW) were studied. The results show that hardness in HAZ is equal to BM, however, hardness becomes higher from fusion line to weld center for finer dendritic structures. The tensile strength sigma(b), yield strength sigma(s) and elongation delta at room temperature (RT) are 810MPa, 392MPa and 30%, which reach 99.6%, 99.7% and 93.8% of based materials', respectively; The sigma(b), sigma(s) and delta at 500 degree C are 678MPa, 300MPa and 26%, which reach 98.1%, 96.8% and 78.8% of based materials', respectively; The welded joint of GH536 has good mechanical properties. Fusion zone is the weak link of welded joint for higher microstructure heterogeneity. Based metal and welded joint break mainly in the way of plastic rupture both at RT and 500 degree C.