Process Design for improving the friction welding weldability of GH4169/TC4 dissimilar joint

This study conducted process design for rotary friction welding of dissimilar materials with “soft/hard” mismatch, resolving poor forming and welding quality issues in typical difficult-to-weld TC4/GH4169 (25 mm) friction welded joints. Analysis identified the primary causes as mismatched plastic deformation on both sides of the interface and excessive formation of brittle intermetallic compounds. The process design approach prioritized achieving physical and mechanical compatibility between dissimilar materials. The proposed solution involved: preheating the GH4169 hot-worked side to 980 °C prior to welding, and selecting welding parameters of low rotational speed (e.g., 400 rpm) and high pressure (e.g., 300 MPa). This process design significantly reduced the intermetallic compound (IMC) layer thickness (∼4 μm) at the interface, effectively suppressing IMC formation and mitigating localized strain caused by mismatched plastic deformation. It achieved an increase in tensile strength (∼440 MPa) for the dissimilar joint, representing a strength improvement of approximately 300%, and revealed the bonding mechanism at the TC4/GH4169 rotary friction welded interface. This work provides design insights for enhancing the weldability of dissimilar “soft/hard” mismatched material assemblies in friction welding.