Improving the interfacial bonding strength of CuCrZr/316L multi-material during laser powder bed fusion by scanning strategies

Copper/steel multi-material components integrate structural load-bearing capability with thermoelectric functionality, offering significant potential for operation under extreme service conditions. However, the discrepancies in physical properties between materials promote crack formation at the interface of copper/steel multi-materials, which significantly degrades their service performance. In this paper, we investigate the effects of interlayer design combined with laser remelting on the evolution of residual stress and mechanical properties of CuCrZr/316L multi-material manufactured by Laser Powder Bed Fusion (LPBF). The surface morphology, element distribution, microhardness, tensile properties, and microstructure of the CuCrZr/316L multi-material interface are analyzed. The results reveal that the laser remelting scanning strategy significantly diminishes residual stress at the CuCrZr/316L multi-material interface. The combination of 90° rotational remelting for 316L and 180° remelting for CuCrZr shows the lowest interfacial stress level, with the maximum value not exceeding the yield strength of 316L. The ultimate tensile strengths of the vertically and horizontally integrated CuCrZr/316L multi-material are 324.3 ± 1.9 MPa and 534.1 ± 3.4 MPa, respectively. In addition, the fracture of vertically bonded specimens occurred in the CuCrZr region, with clear evidence of necking. The fusion zone shows the highest microhardness among all samples, with an average microhardness of 177.64 ± 12.04 HV. The findings of the research provide valuable scanning strategies for enhancing the mechanical properties of copper/steel multi-materials and support the reliable fabrication of high-performance multi-material components.