A novel method to relieve residual stress in dissimilar brazed joint via micro-scale additive manufacturing

To alleviate residual stress of ZrO₂/GH536 brazed joints, the micro-scale structures were fabricated on ZrO₂ via selective laser melting technology before its vacuum brazing with GH536 superalloy. The effects of micro-scale structures on the interfacial microstructure and residual stress of brazed joints were studied. The characterization results indicated that due to its reaction with excessive Ti elements from filler, the micro-scale structures prevented the detrimental effect of over-thick brittle reaction layer on the mechanical properties of joints. Furthermore, the Invar effect of the micro-scale structures facilitated the transfer of residual stress from the ceramic side to the micro-scale structures. According to the numerical simulation results, the maximum residual stress in the brazed joint with micro-scale structures decreased from 622 MPa to 310 MPa. As a result, the fracture path was changed from the flat shape to zigzag. This work reveals the stress-relaxed mechanism of micro-scale structures and provides a new method for fabricating the ceramic/metal joints with low residual stress.