Friction Stir Welding of Laser Powder Bed Fusion Additively Manufactured Copper Alloys

CuNiSiCr alloy fabricated via laser powder bed fusion (LPBF) combines excellent thermal and electrical conductivity with good mechanical strength, making it well‐suited for advanced components in the energy and aerospace sectors. However, the limited build volume of LPBF systems constrains the size of the producible parts. Friction stir welding (FSW) enables the assembly of larger additively manufactured structures without the drawbacks of fusion‐based welding. Although FSW has been applied to LPBF aluminum and titanium alloys, its use in copper‐based systems remains unexplored. In this context, the effectiveness of FSW in joining LPBF CuNiSiCr alloy was investigated using welding speeds of 100 and 500 mm/min at a tool rotation speed of 900 rpm. FSW effectively eliminated porosity, refined the microstructure (2.8‐8 μm), and improved hardness (170 HV versus 84 HV in the as‐built alloy) within the welds through intense plastic deformation and recrystallization. XRD analysis showed a reduction in lattice strain and a {111} texture reorientation after welding. FSW improved mechanical strength, albeit at the expense of ductility: tensile strengths of 245 MPa at 100 mm/min and 235 MPa at 500 mm/min, with elongations at fracture of 7.3 and 7.9%, respectively (versus 216 MPa and 14.2% in the as‐built alloy). These enhancements, attributed to the combined effects of porosity reduction and grain refinement, demonstrate that FSW could be an effective method for assembling large‐scale LPBF CuNiSiCr components.