Investigation on dissimilar EBW of AM-to-wrought Ti-6Al-4V alloys: process optimization, microstructural evolution, and engineering feasibility for complex structures
摘要
The integration of additively manufactured (AM) components with traditional wrought structures is cost-effective and essential for the next-generation aerospace assemblies, yet the engineering feasibility of such dissimilar joining remains underexplored. This study investigates the dissimilar electron beam welding (EBW) of laser powder bed fusion (L-PBF) and wrought Ti-6Al-4V alloys, transitioning from simple plates to complex tubular structures. The research demonstrated that joint reliability and fracture behavior were fundamentally governed by the energy density, precisely controlled through the optimization of welding speed and beam current. Microstructural analysis revealed that specimens welded with an optimized moderate heat input produced refined martensitic α′ laths with widths of 2–3 μm in the fusion zone (FZ). These joints achieved superior mechanical performance, with elongations consistently exceeding 10% and fracture occurring safely within the AM base metal. In contrast, higher energy density driven by increased current or reduced welding speed resulted in coarse and wide α′ laths (> 3 μm), leading to brittle failure within the FZ and reduced ductility (< 10%). By identifying the critical process window (16 mA current and 1000 mm/min speed), this work established a technical foundation for the reliable integration of hybrid AM-to-wrought structures in aerospace engineering applications.
HighlightsDissimilar EBW of L-PBF and wrought Ti-6Al-4V alloy was successfully performed. Optimal speed of 1000 mm/min and 16 mA current refined the α′ martensite in FZ Joints achieved 975±18 MPa UTS and 12.2% elongation via process control. Feasibility was verified from simple plates to complex tubular structures.