Innovative hybrid method to produce ultra-fine grained metal sheets for micro forming

For micro forming process, the initial material of sheet metal is desired, with the thickness below 1 mm. Miniature parts have tight dimensional tolerances and require low surface roughness. These qualities are relatively easy to achieve if the material of the sheets used are ultra-fine grained. This paper introduces a I-ECAP-R method to produce the above mentioned sheet metal. The method consists of sequential use of two multistage processes. The first process includes incremental pressing of a 3 mm thick sheet metal. The second one is multi-stage rolling to flatten the sheets. Initial runs using 1050 Aluminium have shown promising results. These were obtained with a help of two invented technological tests: MB, micro-blanking with a blank holder and MTE, micro-extrusion with tension. In both tests. The maximum shaping force increased by 16.5 % and 24.7 %, respectively, and the tendency to locate deformations decreased, as evidenced by the shift of the points of maximum force in the direction of the punch displacement by 26.4 % and 4.7 %, respectively. SEM studies of the fracture surfaces did not show significant differences in the nature of deformation processes ended with loss of cohesion. Both the UFG and CG material show similar bundle fracture.