Interfacial healing mechanisms during vacuum diffusion bonding of dissimilar duplex stainless steels (DSS) S32304 and S32750 are systematically investigated over a temperature range of 800–1100 °C. The results reveal a strong temperature dependence of atomic diffusion and microstructural evolution. The diffusion coefficient of key alloying elements (Cr, Mo, Ni) increased by 11.3 times (from 1.02 × 10 −15 m 2 s −1 at 800 °C to 1.15 × 10 −14 m 2 s −1 at 1100 °C), which significantly enhanced grain boundary migration and promoted the shrinkage and eventual closure of interfacial voids. Consequently, the interfacial bonding ratio dramatically improved from 25.4% to 91.0%, leading to a progressive enhancement in mechanical properties, with the joint shear strength reaching 813 MPa and microhardness reaching 254 HV. Crucially, at 1100 °C, dynamic recrystallization (DRX) is identified as the dominant healing mechanism, with a recrystallized fraction of 78% at the interface. This process facilitated complete microstructural integration and the formation of a high‐integrity metallurgical bond. This article provides direct evidence establishing DRX as the central mechanism for interfacial healing in diffusion‐bonded dissimilar DSS. At 1100 °C, a high‐strength, defect‐free joint is obtained, providing significant insights for selecting temperatures in solid‐state joining processes.
Wei et al. (2026) studied this question.