Recrystallization and grain growth at the interface of a bimetallic colaminated strip composed of two different Fe-Ni alloys

Abstract

Roll bonding is a solid-state welding process widely used to manufacture layered metal composites. Particular properties may thus be obtained using the physical features of each material of the composite. Bimetal plates consisting of two different Fe-Ni alloys were made by roll bonding followed by heat treatment for 90 minutes at various annealing temperatures. The effects of post-rolling heat treatments on the bonding strength of a bimetal strip were investigated in relation to the interface microstructure evolution. Both recrystallization and grain growth took place at the interface during annealing. In particular, nucleation of new grains as well as growing grains crossing the interface may have contributed to the improvement of the bonding strength. Moreover, diffusion through the interface was found to drastically enhance the bonding strength from 850°C up to 1050°C. However, excessive grain growth associated to porosity occurrence probably caused the saturation of the bonding strength beyond 1050°C.