Improving the bonding characteristics of the friction-welded 2A14 Al alloy/steel interface by enabling mutual deformation

Present study proposed a mutual plastic deformation method for friction-welded joints of 2A14 Al alloy and steel, incorporating a Ni interlayer to enable dual-interfacial deformation at the Al/Ni and Ni/steel interfaces. Compared to joints without Ni, which display a Fe-Al-O amorphous layer and a 100 nm-thick Al₂Cu layer at the interface with no grain refinement in the steel, dual-interfacial mutual deformation leads to finer grains. Additionally, it results in a thinner, semi-coherent Al-Ni-Cu ternary intermetallic layer, approximately 23 nm thick. This microstructural evolution results in a tensile strength of ∼354 MPa, a significant reduction in residual stress and improved low-cycle fatigue properties. This approach also holds promise for enhancing the properties of other dissimilar metal joints.