Evaluation of Laser Powder Bed Fusion-Fabricated 316L/CuCrZr Bimetal Joint

While a tensile test revealing joint fracture at the base material may indicate good joint quality under certain circumstances, this conclusion might overlook the importance of examining the joint interface because exceptions can occur when one side is significantly softer. This study investigates the fabrication of a 316L/CuCrZr bimetal structure using the laser powder bed fusion (LPBF) process. Cracks were observed at the joint interface. The microhardness measured approximately 200 HV at the cracked interface and 100 HV on the CuCrZr side. Tensile testing showed that fractures occurred on the CuCrZr side, despite the presence of cracks at the bonding interface of the 316L/CuCrZr bimetal joint. Spheroids of 316L and Cu were found at the interface due to the Fe-Cu immiscibility system. This immiscibility was the main reason for the formation of cracks. This highlights the need for a thorough microstructural examination of the bonding to ensure a comprehensive quality assessment. The LPBF-fabricated 316L/CuCrZr bimetal joint exhibits a yield strength of 203.0 MPa, a UTS of 287.5 MPa, and an elongation of 15.3%.