Grain-structure evolution of brazing-treated A4343/A3003/A4343 aluminum brazing sheets rolled with different reductions

摘要

The grain-structure evolution of three-layered A4343(clad)/A3003(core)/A4343(clad) aluminum brazing sheets was studied by means of electron backscatter diffraction. Three different samples were prepared by cold rolling with 17%, 22%, and 44% reduction, and the brazing treatment was carried out in form of differential scanning calorimetry. Orientation maps of the clad and the core suggested that the grains in the melted and re-solidified clad did not grow epitaxially from the core in case of the 17% and 22% cold-rolled samples. In contrast, the grains in the 44% cold-rolled sample seemed to have been formed by epitaxial growth from the core. Kernel average misorientation (KAM) analysis revealed that the samples cold rolled with 17% and 22% reduction retained a deformed microstructure in the core even after the brazing treatment, but the core of the 44% cold-rolled sample was composed of coarse elongated grains, free from any substructure. The dissolution depth corresponding to the thickness of the core affected by the brazing treatment was proportional to the average KAM of the core.