電析Niの超塑性変形を利用した鉄鋼材料の低温接合

抄録

In the field of diffusion bonding of steel materials, there is a need to develop processes for bonding at low temperatures and in air. In this study, low temperature joining of steel materials was performed using electrodeposited Ni as an intermediate material, which exhibits superplasticity. At first, we examined the adhesion of electrodeposited Ni to steel substrates. The adhesion shear strength of 452 MPa was achieved by subjecting the steel substrate to an alkaline bath prior to electrodeposition of Ni. Subsequently, the bonding was carried out at 450 °C in air and at a strain rate of 1.0×10−4 s−1. The bond strength was measured by shear test and achieved 102 MPa. The specimens fractured not at the bonding interface, but within the electrodeposited Ni. This finding suggests that the bonding process employed in this study effectively mitigated the detrimental effects on bondability resulting from the presence of an oxide film on the bonding surfaces. It is postulated that by appropriately polishing the bonding surfaces and augmenting the compressive strain, the amount of microplastic deformation at the bonding surfaces is increased, resulting in sufficient oxide film rupture at the bonding surfaces and enhanced bondability. This novel bonding process enables the bonding of steel materials at temperatures below the conventional diffusion bonding threshold.