Combination forming rolling of metal aluminum at room temperature

Abstract

The elastic deformation of rollers makes it difficult to prepare ultra-thin metal strips by using conventional methods, and various methods have been used to obtain thinner rolled pieces, such as reducing the roll diameter, increasing the number of support rollers, and increasing the rigidity of rollers and frames; however, these methods complicate the preparation of ultra-thin strips. In this study, we adopt a new method of combination forming rolling, in which three kinds of technological measures, namely, the compression effect of ordinary rolling, shear effect of asymmetrical rolling, and drawing effect of a large tensile force, are jointly applied to the rolling deformation zone to generate a stress state that easily satisfies the yield condition so as to maintain the sustainability of pressed deformation. In order to verify the feasibility of this method, an annealed industrial pure aluminum plate was subjected to combination forming rolling at room temperature. The experimental results showed that in the absence of intermediate annealing, the 1100 aluminum plate with an initial thickness of 6.5 mm was rolled into an ultra-thin strip with a thickness of 17 μm, having a smooth surface, good shape, and no edge cracks. With combination forming rolling, the plate showed an extension of as high as 38235% and a true strain of 5.95, fully reflecting the super deformability of the combination forming rolling method. During the occurrence of severe plastic deformation, the microstructure inside the ultra-thin metal Al strip also underwent evolution—from the original coarse equiaxed crystals to flat lath crystals and sub-microcrystals and ultimately to nanocrystals. The combination forming rolling method, which involves a large strain, extreme extensibility and nano-crystallization, is expected to become an important new means suitable for severe plastic deformation.