A new method for dissimilar friction welding weldability evaluation and optimization by analytical calculation

The selection of friction welding parameters for dissimilar materials has traditionally relied on empirical experience, with limited theoretical underpinning. This study proposes a novel analytical framework for assessing the weldability of dissimilar materials, providing predictive capabilities that transcend conventional trial-and-error methods. By introducing the concept of constitutive equation intersections for the materials to be joined, a qualitative criterion for weldability is established. The solution of these equations not only offers a robust foundation for evaluating the compatibility of dissimilar metals but also guides the selection of critical welding parameters, including welding pressure and friction speed. The results of the calculations are discussed using a variety of material groupings as case studies. Using TC4/GH4169 as a typical grouping of difficult-to-weld materials, a secondary friction welding process with the addition of a transition layer was developed. This innovative process design effectively mitigates interface defects and significantly enhances joint performance. Notably, the tensile strength of the weld is improved from less than 200 MPa to an impressive 506 MPa, demonstrating the transformative potential of this approach. These findings provide a scientific basis for the optimization of friction welding processes, paving the way for stronger, defect-free joints in dissimilar material systems.