Advanced microstructural analysis of CuCrZr and 304 stainless steel dissimilar welds via transmission electron microscopy

This study characterizes CuCrZr/304 stainless steel dissimilar welds using HR-TEM and EDS. A 1.5–2.0 μm interfacial diffusion layer was identified, driven primarily by Cu migration. Analysis confirmed the formation of brittle Fe-Cu intermetallic compounds (FeCu 3 , Fe 2 Cu 5 ) and significant sulfur segregation (FeS, Cu 2 S), leading to grain boundary embrittlement and hot cracking. Furthermore, high-density dislocation networks and twin boundaries indicated strain-induced martensitic transformation in the heat-affected zone. Based on these nanoscale insights, employing diffusion barriers and post-weld heat treatment is proposed to mitigate defects and enhance joint stability.