Effect of Welding and Post-weld Heat Treatment on Tensile Properties of Nimonic 263 at Room and Elevated Temperatures

Abstract

Nimonic 263 has been developed for the improved ductility in welded assemblies and is a candidate material for gas turbine combustor and transition pieces along with its good weldability and mechanical properties at room and elevated temperatures. In this study, the tensile behavior of an as-welded Nimonic 263 specimen at room temperature and 1053 K (780°C) was examined in conjunction with microstructural evolution during welding and postweld heat treatment (PWHT). With the welding and the PWHT, the yield strength (YS), ultimate tensile strength (UTS), and tensile elongation of Nimonic 263 varied in a complex manner. It was observed that the PWHT of resolutionization at 1423 K (1150°C) for 2 hours gave the highest YS and UTS values, whereas the tensile elongation was the lowest, at both testing temperatures. With increasing resolutionization time, the YS and UTS tended to decrease along with the increase in tensile ductility. The tensile behaviors of as-welded Nimonic 263 specimens was affected by several factors, including grain size, residual stress, possible microsegregation of c¢ forming elements, a tendency for interdendritic or intergranular fracture and a morphological change in both M 23 C 6 and MC type carbides, depending on the testing temperature and the PWHT. The complex changes in tensile properties of Nimonic 263 with welding and PWHT at room temperature and 1053 K (780°C) were discussed based on the micrographic and fractographic observations.

The correlated mechanism of creep fracture and microstructure evolution for precipitated Nimonic 263 superalloy welding joint

“…Kim et al [14] studied the effect of post weld heat treatment (PWHT) at 810°C on the microstructure of alloy 263 gas tungsten arc welding (GTAW) weld joint, where they primarily observed two kinds of carbides in weld metal: the MC mainly distributed on the grain boundary and dendrite gap, and M 23 C 6 distributed near the grain boundary. The results are consistent with the study of microstructure of N263 GTAW weld joint by Jeon et al [15].…”

Evolution of γ′ Particles in Ni-Based Superalloy Weld Joint and Its Effect on Impact Toughness During Long-Term Thermal Exposure

“…Although there are lots of papers about Nickelbased superalloy weld joints [13][14][15], few studies are concerned about the weld joint of N263. Jeon et al [16] studied the microstructure and tensile properties of N263 weld joint after post-weld heat treatment (PWHT) at room temperature and 780 °C. They reported that the PWHT of solution at 1150 °C for 2 h gave the highest strength values.…”

Resistance spot welding of Nimonic 263 nickel-based superalloy: microstructure and mechanical properties

“…Therefore, it can be concluded that the Mo-Ti rich carbides are formed in the inter-dendritic area. The formation of Ti-Mo rich MC carbides is also reported in the fusion zone of arc welded Nimonic 263 [23]. The formation of carbide phases can be explained by the segregation tendency of the various elements during solidification.…”

“…The effect of welding thermal cycle on the microstructure evolution including segregation phenomena and consequent second phase formation in the inter-dendritic regions, liquation phenomena and solidification cracking should be investigated. Although there are some works on arc welding behaviour of Nimonic 263 [22, 23], no published research study can be found on RSW of this alloy. This paper addresses the effect of resistance spot welding on the microstructure and mechanical properties of annealed Nimonic 263 nickel-based superalloy.…”