Bonding behavior of Bi-metal-deposits produced by hybrid cold spray additive manufacturing

Cold spraying (CS) is one of the most recently used additive manufacturing (AM) processes that allow forming large 3D objects efficiently without severe thermal effects. However, due to some limitations of the CSAM process, it is difficult to achieve the desired geometry with high precision. As a potential solution to this issue, CSAM process coupled machining, that is, hybrid addition and subtraction manufacturing, is proposed to achieve desired accuracy and reliable shape. Therefore, it is necessary to assess the mechanical reliability of multilayer deposits deposited by CSAM + machining processes before that. In this work, different bi-deposits were obtained via hybrid CSAM. The adhesion performance at the bonding interface of bi-deposits was assessed by mechanical measurements including tensile and shear failure tests. The morphology of fracture surfaces was observed by scanning electron microscope. The results showed that CSAM bi-deposits with different materials and different interface states had different adhesion effects: the adhesion effect of soft/soft bi-deposits was the best, followed by hard/hard bi-deposits, and hard/soft bi-deposits were the worst. This is due to the fact that hard CS deposits are difficult to deform, making it difficult to embed with particles and build a good bonding; The bonding interface without any treatment had the best adhesion effect, followed by the milling + grit-blasting surfaces, and the milling surfaces performed the worst. The interface's roughness is the major influencing factor. Roughening of bonding interface promotes more embedding and interlocking effect, which improves bonding strength.