Improving the performance of electrically assisted pressure joining for dissimilar ferrous alloys by local modification of resistance heating

The performance of electrically assisted pressure joining (EAPJ) of dissimilar stainless steels, SUS316L and SUS410, is enhanced by introducing a circumferential groove near the joining interface of the SUS316L specimen. The results indicate that the groove effectively concentrates resistance heating and shifts the maximum temperature from the SUS316L matrix toward the joining interface region, resulting in improved temperature symmetry and deformation balance between the two base materials (BMs) with respect to the joining interface. Microstructural analysis reveals an approximately 80% increase in diffusion layer thickness, together with enhanced dynamic recrystallization near the joint interface. Consequently, the mechanical performance of the joint is significantly improved (tensile strength: 660 MPa; shear strength: 700 MPa), with the tensile fracture mode shifting from interfacial fracture to BM fracture in the SUS316L matrix. These results confirm the feasibility of groove-enhanced resistance heating for improving EAPJ performance and suggest a practical EAPJ strategy for joining dissimilar material combinations with large differences in material properties.