Microstructure evolution and interfacial healing mechanism of GH4098 Ni-base superalloy joints produced by hot-compression bonding

The influence of hot compression temperature and strain on interfacial healing mechanism of GH4098 Ni-based superalloy joints during hot-compression bonding (HCB) is investigated. Increasing both the hot compression temperature and strain promotes interfacial healing at the bonding interface. Complete interfacial healing is achieved at 50% strain under the hot compression conditions of 1100 °C and 0.01 s⁻¹, and the mechanical properties of bonding joint can reach the same level as the base material. During HCB, grain boundaries migrate across the interface and eliminate the original interface through discontinuous dynamic recrystallization (DDRX), thereby achieving interfacial healing. After hot compression, the original mixed-grain forged microstructure of GH4098 becomes homogenized through the combined action of DDRX and continuous dynamic recrystallization (CDRX), resulting in a uniform grain size distribution. Guided by these results, industrial production can effectively achieve seamless joining of GH4098 forgings, thereby obtaining large-scale structural components with superior performance. • Elevated temperature and strain enhance interfacial healing during hot compression. • Complete interfacial healing occurs at 50% strain, 1100 ℃, and 0.01 s -1 . • Grain coarsening above 1150 ℃ reduces the bonding strength of GH4098 joints. • Strain-induced grain boundary migration eliminates the original interface.