A New Method of Bonding SUS304 Stainless Steels Using Nickel-Iron Alloy Plating and Evaluation of the Mechanical Properties of the Bonds

We investigated a novel bonding technique using Fe-Ni alloy plating as an alternative method for stainless steel bonding. This bonding process involves bonding at approximately 55 °C followed by annealing at temperatures above 300 °C, which is relatively low compared with conventional methods. Previous studies utilized bonding through Ni plating (NMPB; Ni Micro-Plating Bonding), which ensured a dense bond by maintaining a consistent growth rate of Ni plating crystals from opposing bonding surfaces, minimizing voids15). However, despite its effectiveness, Ni plating bonding resulted in only about one-third of the strength of the base material. In this study, we evaluated the bonding strength through shear tests by bonding stainless steel plates and wires with Fe-Ni alloys ranging from 41 to 87 wt% Ni. The shear strength of the joint as-plated, without heat treatment, was 173 MPa for Fe-87 wt% Ni alloy plating and 240 MPa for Fe-68 wt% Ni alloy plating, compared to 114 MPa for Ni plating. Thus, Fe-Ni alloy plating exhibited approximately 1.5 to 2.1 times the shear strength of Ni plating. Conversely, Fe-41 wt% Ni alloy plating showed significantly lower strength at 32 MPa. After heat treatment ranging from 300 to 800 °C, the shear strength increased to 183-236 MPa for Ni plating, 182-292 MPa for Fe-87 wt% Ni alloy plating and Fe-68 wt% Ni alloy plating, while Fe-41 wt% Ni alloy plating increased to around 117 MPa.